Repository: pykeen/pykeen
Issue: Update ogb-wikikg to ogb-wikikg2
Root cause: External Dependency Breakage

**Describe the bug**

Since `ogb-wikikg` is deprecated (as mentioned in https://ogb.stanford.edu/docs/linkprop/), loading `pykeen.dataset.OGBWikiKG` raises `ValueError`.
> ogbl-wikikg2 is available for ogb>=1.2.4. The previous version ogbl-wikikg is deprecated for ogb>=1.2.4 due to a bug in negative samples of validation/test sets (many nodes are not sampled as negative samples). The issue is resolved in ogbl-wikikg2. The deprecated leaderboard of ogbl-wikikg can be found here.

**To Reproduce**
Run `python -m pykeen.datasets.ogb` and following error occurs:

```
/db2/users/seokjinhan/.env/conda/envs/pykeen/lib/python3.9/runpy.py:127: RuntimeWarning: 'pykeen.datasets.ogb' found in sys.modules after import of package 'pykeen.datasets', but prior to execution of 'pykeen.datasets.ogb'; this may result in unpredictable behaviour
  warn(RuntimeWarning(msg))
/db2/users/seokjinhan/develop/pykeen/src/pykeen/datasets/ogb.py:123: DeprecationWarning: `np.str` is a deprecated alias for the builtin `str`. To silence this warning, use `str` by itself. Doing this will not modify any behavior and is safe. If you specifically wanted the numpy scalar type, use `np.str_` here.
Deprecated in NumPy 1.20; for more details and guidance: https://numpy.org/devdocs/release/1.20.0-notes.html#deprecations
  dtype=np.str,
/db2/users/seokjinhan/develop/pykeen/src/pykeen/datasets/ogb.py:110: DeprecationWarning: `np.str` is a deprecated alias for the builtin `str`. To silence this warning, use `str` by itself. Doing this will not modify any behavior and is safe. If you specifically wanted the numpy scalar type, use `np.str_` here.
Deprecated in NumPy 1.20; for more details and guidance: https://numpy.org/devdocs/release/1.20.0-notes.html#deprecations
  triples = np.stack([head_triples, x['relation'], tail_triples], axis=1).astype(np.str)
OGBBioKG (create_inverse_triples=False)
Name        Entities    Relations      Triples
----------  ----------  -----------  ---------
Training    93773       51             4762677
Testing     93773       51              162870
Validation  93773       51              162886
Total       -           -              5088433
Head          Relation  tail
----------  ----------  -------------
disease:0            0  protein:7051
disease:1            0  protein:8658
disease:10           0  protein:1030
disease:10           0  protein:11136
disease:10           0  protein:11217

Traceback (most recent call last):
  File "/db2/users/seokjinhan/.env/conda/envs/pykeen/lib/python3.9/runpy.py", line 197, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/db2/users/seokjinhan/.env/conda/envs/pykeen/lib/python3.9/runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "/db2/users/seokjinhan/develop/pykeen/src/pykeen/datasets/ogb.py", line 160, in <module>
    _main()
  File "/db2/users/seokjinhan/.env/conda/envs/pykeen/lib/python3.9/site-packages/click/core.py", line 1137, in __call__
    return self.main(*args, **kwargs)
  File "/db2/users/seokjinhan/.env/conda/envs/pykeen/lib/python3.9/site-packages/click/core.py", line 1062, in main
    rv = self.invoke(ctx)
  File "/db2/users/seokjinhan/.env/conda/envs/pykeen/lib/python3.9/site-packages/click/core.py", line 1404, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/db2/users/seokjinhan/.env/conda/envs/pykeen/lib/python3.9/site-packages/click/core.py", line 763, in invoke
    return __callback(*args, **kwargs)
  File "/db2/users/seokjinhan/develop/pykeen/src/pykeen/datasets/ogb.py", line 156, in _main
    _cls(cache_root='/tmp/graph-benchmark').summarize()
  File "/db2/users/seokjinhan/develop/pykeen/src/pykeen/datasets/base.py", line 145, in summarize
    print(self.summary_str(title=title, show_examples=show_examples), file=file)
  File "/db2/users/seokjinhan/develop/pykeen/src/pykeen/datasets/base.py", line 128, in summary_str
    rows = self._summary_rows()
  File "/db2/users/seokjinhan/develop/pykeen/src/pykeen/datasets/base.py", line 123, in _summary_rows
    zip(('Training', 'Testing', 'Validation'), (self.training, self.testing, self.validation))
  File "/db2/users/seokjinhan/develop/pykeen/src/pykeen/datasets/base.py", line 257, in training
    self._load()
  File "/db2/users/seokjinhan/develop/pykeen/src/pykeen/datasets/ogb.py", line 49, in _load
    dataset = LinkPropPredDataset(name=self.name, root=self.cache_root)
  File "/db2/users/seokjinhan/.env/conda/envs/pykeen/lib/python3.9/site-packages/ogb/linkproppred/dataset.py", line 31, in __init__
    raise ValueError(error_mssg)
ValueError: Invalid dataset name ogbl-wikikg.
Available datasets are as follows:
ogbl-ppa
ogbl-collab
ogbl-citation2
ogbl-wikikg2
ogbl-ddi
ogbl-biokg
```

**Expected behavior**
The dataset should be loaded without error.

**Environment:**

```
| Key             | Value                    |
|-----------------|--------------------------|
| OS              | posix                    |
| Platform        | Linux                    |
| Release         | 4.15.0-120-generic       |
| Time            | Thu Aug 26 14:48:38 2021 |
| Python          | 3.9.6                    |
| PyKEEN          | 1.5.1-dev                |
| PyKEEN Hash     | fbd14135                 |
| PyKEEN Branch   | master                   |
| PyTorch         | 1.9.0+cu102              |
| CUDA Available? | true                     |
| CUDA Version    | 10.2                     |
| cuDNN Version   | 7605                     |
```

**Additional information**
None.


Hi @raifthenerd, thanks for being patient. We just pushed an update to solve this