Some languages in wikipedia dataset are not loading 
 Hi,

I am working with the `wikipedia` dataset and I have a script that goes over 92 of the available languages in that dataset. So far I have detected that `ar`, `af`, `an` are not loading. Other languages like `fr` and `en` are working fine. Here's how I am loading them:

```
import nlp

langs = ['ar'. 'af', 'an']

for lang in langs:
    data = nlp.load_dataset('wikipedia', f'20200501.{lang}', beam_runner='DirectRunner', split='train') 
    print(lang, len(data))
```

Here's what I see for 'ar' (it gets stuck there):
```
Downloading and preparing dataset wikipedia/20200501.ar (download: Unknown size, generated: Unknown size, post-processed: Unknown sizetotal: Unknown size) to /home/gaguilar/.cache/huggingface/datasets/wikipedia/20200501.ar/1.0.0/7be7f4324255faf70687be8692de57cf79197afdc33ff08d6a04ed602df32d50...
```

Note that those languages are indeed in the list of expected languages. Any suggestions on how to work around this? Thanks! 
 I think the work around  as suggested in the issue [#886] is not working for several languages, such as `id`. For example, I tried all the dates to download dataset for `id` langauge from the following link: (https://github.com/huggingface/datasets/pull/886) [https://dumps.wikimedia.org/idwiki/](https://dumps.wikimedia.org/idwiki/ )

>  >>> dataset = load_dataset('wikipedia', language='id', date="20210501",  beam_runner='DirectRunner')
WARNING:datasets.builder:Using custom data configuration 20210501.id-date=20210501,language=id
Downloading and preparing dataset wikipedia/20210501.id (download: Unknown size, generated: Unknown size, post-processed: Unknown size, total: Unknown size) to /Users/.cache/huggingface/datasets/wikipedia/20210501.id-date=20210501,language=id/0.0.0/2fe8db1405aef67dff9fcc51e133e1f9c5b0106f9d9e9638188176d278fd5ff1...
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/opt/anaconda3/envs/proj/lib/python3.9/site-packages/datasets/load.py", line 745, in load_dataset
    builder_instance.download_and_prepare(
  File "/Users/opt/anaconda3/envs/proj/lib/python3.9/site-packages/datasets/builder.py", line 574, in download_and_prepare
    self._download_and_prepare(
  File "/Users/opt/anaconda3/envs/proj/lib/python3.9/site-packages/datasets/builder.py", line 1139, in _download_and_prepare
    super(BeamBasedBuilder, self)._download_and_prepare(
  File "/Users/opt/anaconda3/envs/proj/lib/python3.9/site-packages/datasets/builder.py", line 630, in _download_and_prepare
    split_generators = self._split_generators(dl_manager, **split_generators_kwargs)
  File "/Users/.cache/huggingface/modules/datasets_modules/datasets/wikipedia/2fe8db1405aef67dff9fcc51e133e1f9c5b0106f9d9e9638188176d278fd5ff1/wikipedia.py", line 420, in _split_generators
    downloaded_files = dl_manager.download_and_extract({"info": info_url})
  File "/Users/opt/anaconda3/envs/proj/lib/python3.9/site-packages/datasets/utils/download_manager.py", line 287, in download_and_extract
    return self.extract(self.download(url_or_urls))
  File "/Users/opt/anaconda3/envs/proj/lib/python3.9/site-packages/datasets/utils/download_manager.py", line 195, in download
    downloaded_path_or_paths = map_nested(
  File "/Users/opt/anaconda3/envs/proj/lib/python3.9/site-packages/datasets/utils/py_utils.py", line 203, in map_nested
    mapped = [
  File "/Users/opt/anaconda3/envs/proj/lib/python3.9/site-packages/datasets/utils/py_utils.py", line 204, in <listcomp>
    _single_map_nested((function, obj, types, None, True)) for obj in tqdm(iterable, disable=disable_tqdm)
  File "/Users/opt/anaconda3/envs/proj/lib/python3.9/site-packages/datasets/utils/py_utils.py", line 142, in _single_map_nested
    return function(data_struct)
  File "/Users/opt/anaconda3/envs/proj/lib/python3.9/site-packages/datasets/utils/download_manager.py", line 218, in _download
    return cached_path(url_or_filename, download_config=download_config)
  File "/Users/opt/anaconda3/envs/proj/lib/python3.9/site-packages/datasets/utils/file_utils.py", line 281, in cached_path
    output_path = get_from_cache(
  File "/Users/opt/anaconda3/envs/proj/lib/python3.9/site-packages/datasets/utils/file_utils.py", line 623, in get_from_cache
    raise ConnectionError("Couldn't reach {}".format(url))
ConnectionError: Couldn't reach https://dumps.wikimedia.org/idwiki/20210501/dumpstatus.json

Moreover the downloading speed for `non-en` language is very very slow. And interestingly the download stopped after approx a couple minutes due to the read time-out. I tried numerous times and the results is same. Is there any feasible way to download non-en language using huggingface?

> File "/Users/miislamg/opt/anaconda3/envs/proj-semlm/lib/python3.9/site-packages/requests/models.py", line 760, in generate
    raise ConnectionError(e)
requests.exceptions.ConnectionError: HTTPSConnectionPool(host='dumps.wikimedia.org', port=443): Read timed out.
Downloading:   7%|████████▎                                                                                                                   | 10.2M/153M [03:35<50:07, 47.4kB/s]