Make UploadFailedError picklable

[birgerbr]

Make UploadFailedError picklable

Motivation

The ray library is not able to handle unpicklable exceptions sufficiently, see ray-project/ray#21075 for a similar issue.

Tests

The PickleUploadFailedTest test case has been added to test_gcs.py.

Checklist

Before you create the PR, please make sure you have:

• Picked a concise, informative and complete title
• Clearly explained the motivation behind the PR
• Linked to any existing issues that your PR will be solving
• Included tests for any new functionality
• Checked that all unit tests pass

[mpenkov]

Hi, can you please make this PR editable for maintainers?

As a maintainer, I'd like to merge the most recent upstream into your PR, but need you to give me permission first.

[birgerbr]

Hi, can you please make this PR editable for maintainers?

As a maintainer, I'd like to merge the most recent upstream into your PR, but need you to give me permission first.

I added you with write permission to https://github.com/Imerso3D/smart_open.
Is that sufficient?

[mpenkov]

Yes, that's a little excessive (you can set it for individual PRs instead of the whole repo) but it will get the job done. Thanks.

[birgerbr]

Yes, that's a little excessive (you can set it for individual PRs instead of the whole repo) but it will get the job done. Thanks.

Thanks for the info. I did not know that. 👍