Repository: huggingface/lighteval
Issue: [BUG] community_tasks not working or example is broken
Root cause: Documentation Deficiency

## Describe the bug

On the README page is an example to run community_tasks. It is:

```bash
lighteval accelerate \
    --model_args "pretrained=HuggingFaceH4/zephyr-7b-beta" \
    --use_chat_template \ # optional, if you want to run the evaluation with the chat template
    --tasks "community|arabic_mmlu:abstract_algebra|5|1" \
    --custom_tasks "community_tasks/arabic_evals" \
    --output_dir "./evals"
```

When I execute this exact command (slightly modified with smaller LLM):

```bash
lighteval accelerate \
    --model_args "pretrained=TinyLlama/TinyLlama-1.1B-Chat-v1.0" \
    --use_chat_template \
    --tasks "community|arabic_mmlu:abstract_algebra|5|1" \
    --custom_tasks "community_tasks/arabic_evals" \
    --output_dir "./evals"
```

I get this error:

```
~/code/git/lighteval$ lighteval accelerate \
    --model_args "pretrained=TinyLlama/TinyLlama-1.1B-Chat-v1.0" \
    --use_chat_template \
    --tasks "community|arabic_mmlu:abstract_algebra|5|1" \
    --custom_tasks "community_tasks/arabic_evals" \
    --output_dir "./evals"
INFO:absl:Using default tokenizer.
INFO:absl:Using default tokenizer.
INFO:absl:Using default tokenizer.
INFO:absl:Using default tokenizer.
INFO:absl:Using default tokenizer.
WARNING:lighteval.logging.hierarchical_logger:main: (0, Namespace(subcommand='accelerate', model_config_path=None, model_args='pretrained=TinyLlama/TinyLlama-1.1B-Chat-v1.0', max_samples=None, override_batch_size=-1, job_id='', output_dir='./evals', push_results_to_hub=False, save_details=False, push_details_to_hub=False, push_results_to_tensorboard=False, public_run=False, results_org=None, use_chat_template=True, system_prompt=None, dataset_loading_processes=1, custom_tasks='community_tasks/arabic_evals', tasks='community|arabic_mmlu:abstract_algebra|5|1', cache_dir=None, num_fewshot_seeds=1)),  {
WARNING:lighteval.logging.hierarchical_logger:  Test all gather {
WARNING:lighteval.logging.hierarchical_logger:    Test gather tensor
WARNING:lighteval.logging.hierarchical_logger:    gathered_tensor tensor([0], device='cuda:0'), should be [0]
WARNING:lighteval.logging.hierarchical_logger:  } [0:00:00.228144]
WARNING:lighteval.logging.hierarchical_logger:  Model loading {
WARNING:lighteval.logging.hierarchical_logger:    Tokenizer truncation and padding size set to the left side.
WARNING:lighteval.logging.hierarchical_logger:    We are not in a distributed setting. Setting model_parallel to False.
WARNING:lighteval.logging.hierarchical_logger:    Model parallel was set to False, max memory set to None and device map to None
WARNING:lighteval.logging.hierarchical_logger:    Using Data Parallelism, putting model on device cuda
WARNING:lighteval.logging.hierarchical_logger:  } [0:00:01.475935]
WARNING:lighteval.logging.hierarchical_logger:  Tasks loading {
WARNING:lighteval.logging.hierarchical_logger:  } [0:00:00.000243]
WARNING:lighteval.logging.hierarchical_logger:} [0:00:01.706154]
Traceback (most recent call last):
  File "/users/philip/miniconda3/envs/lighteval-git/bin/lighteval", line 8, in <module>
    sys.exit(cli_evaluate())
  File "/users/philip/miniconda3/envs/lighteval-git/lib/python3.10/site-packages/lighteval/__main__.py", line 58, in cli_evaluate
    main_accelerate(args)
  File "/users/philip/miniconda3/envs/lighteval-git/lib/python3.10/site-packages/lighteval/logging/hierarchical_logger.py", line 175, in wrapper
    return fn(*args, **kwargs)
  File "/users/philip/miniconda3/envs/lighteval-git/lib/python3.10/site-packages/lighteval/main_accelerate.py", line 78, in main
    pipeline = Pipeline(
  File "/users/philip/miniconda3/envs/lighteval-git/lib/python3.10/site-packages/lighteval/pipeline.py", line 126, in __init__
    self._init_tasks_and_requests(tasks=tasks)
  File "/users/philip/miniconda3/envs/lighteval-git/lib/python3.10/site-packages/lighteval/pipeline.py", line 175, in _init_tasks_and_requests
    _, tasks_groups_dict = get_custom_tasks(custom_tasks)
  File "/users/philip/miniconda3/envs/lighteval-git/lib/python3.10/site-packages/lighteval/tasks/registry.py", line 195, in get_custom_tasks
    custom_tasks_module = create_custom_tasks_module(custom_tasks=custom_tasks)
  File "/users/philip/miniconda3/envs/lighteval-git/lib/python3.10/site-packages/lighteval/tasks/registry.py", line 185, in create_custom_tasks_module
    return importlib.import_module(custom_tasks)
  File "/users/philip/miniconda3/envs/lighteval-git/lib/python3.10/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1004, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'community_tasks/arabic_evals'
```

## To Reproduce
see above, I have the same issues with "my" [german_rag_evals.txt](https://github.com/huggingface/lighteval/blob/main/examples/tasks/all_german_rag_evals.txt) tests. Can you please check and provide a working example how to use community tasks. Something seems to be broken at the moment.

## Expected behavior
the test should start

## Version info
Linux, last lighteval commit e6b599a1448a8b06141cb4f678866ae15b0c5863 from Aug 21, 2024


This command seems to work:

```bash
lighteval accelerate \
    --model_args "pretrained=TinyLlama/TinyLlama-1.1B-Chat-v1.0,trust_remote_code=True" \
    --use_chat_template \
    --tasks "community|arabic_mmlu:abstract_algebra|5|1" \
    --custom_tasks "community_tasks/arabic_evals.py" \
    --output_dir "./evals"
```

I added the missing .py and had to add `,trust_remote_code=True`.
So it is just a small issue in the example.

Thanks for the issue, should be fixed in #300 :)