Unable to access some model weights

When loading some models such as `hmax` or `VideoMAE-V1-B` (and I presume many others), the error of a following kind is thrown:

```Traceback (most recent call last):
File "C:\Users\loennqvi\Anaconda3\envs\brain-score\lib\site-packages\brainio\fetch.py", line 78, in download_boto
self.download_boto_config(config=None)
File "C:\Users\loennqvi\Anaconda3\envs\brain-score\lib\site-packages\brainio\fetch.py", line 94, in download_boto_config
with tqdm(total=obj.content_length, unit='B', unit_scale=True,
File "C:\Users\loennqvi\Anaconda3\envs\brain-score\lib\site-packages\boto3\resources\factory.py", line 381, in property_loader
self.load()
File "C:\Users\loennqvi\Anaconda3\envs\brain-score\lib\site-packages\boto3\resources\factory.py", line 565, in do_action
response = action(self, *args, **kwargs)
File "C:\Users\loennqvi\Anaconda3\envs\brain-score\lib\site-packages\boto3\resources\action.py", line 88, in __call__
response = getattr(parent.meta.client, operation_name)(*args, **params)
File "C:\Users\loennqvi\Anaconda3\envs\brain-score\lib\site-packages\botocore\client.py", line 553, in _api_call
return self._make_api_call(operation_name, kwargs)
File "C:\Users\loennqvi\Anaconda3\envs\brain-score\lib\site-packages\botocore\client.py", line 1009, in _make_api_call
raise error_class(parsed_response, operation_name)
botocore.exceptions.ClientError: An error occurred (404) when calling the HeadObject operation: Not Found

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "C:\Users\loennqvi\Anaconda3\envs\brain-score\lib\site-packages\brainio\fetch.py", line 84, in download_boto
self.download_boto_config(config=unsigned_config)
File "C:\Users\loennqvi\Anaconda3\envs\brain-score\lib\site-packages\brainio\fetch.py", line 94, in download_boto_config
with tqdm(total=obj.content_length, unit='B', unit_scale=True,
File "C:\Users\loennqvi\Anaconda3\envs\brain-score\lib\site-packages\boto3\resources\factory.py", line 381, in property_loader
self.load()
File "C:\Users\loennqvi\Anaconda3\envs\brain-score\lib\site-packages\boto3\resources\factory.py", line 565, in do_action
response = action(self, *args, **kwargs)
File "C:\Users\loennqvi\Anaconda3\envs\brain-score\lib\site-packages\boto3\resources\action.py", line 88, in __call__
response = getattr(parent.meta.client, operation_name)(*args, **params)
File "C:\Users\loennqvi\Anaconda3\envs\brain-score\lib\site-packages\botocore\client.py", line 553, in _api_call
return self._make_api_call(operation_name, kwargs)
File "C:\Users\loennqvi\Anaconda3\envs\brain-score\lib\site-packages\botocore\client.py", line 1009, in _make_api_call
raise error_class(parsed_response, operation_name)
botocore.exceptions.ClientError: An error occurred (403) when calling the HeadObject operation: Forbidden

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "C:\Users\loennqvi\Anaconda3\envs\brain-score\lib\site-packages\brainio\fetch.py", line 88, in download_boto
raise Exception([e_signed, e_unsigned])
Exception: [ClientError('An error occurred (404) when calling the HeadObject operation: Not Found'), ClientError('An error occurred (403) when calling the HeadObject operation: Forbidden')]
python-BaseException
```

This does not seem to happen for all users (e.g., on a different user & machine without `aws` configuration), but it does happen on my machine with an `aws` user configured. It seems like brainio attempts to access the file both with and without my credentials, and both fail for some reason (even though the model files should be publicly accessible).

Start by reproducing the failure while loading hmax or VideoMAE-V1-B, then inspect brainio/fetch.py at download_boto and download_boto_config, especially the calls reported at lines 78–94. Compare behavior with and without AWS configuration and verify whether publicly accessible model weights can be loaded successfully without the 404/403 fallback errors.

Written by the indexing model from the issue text.