[CI] Create gh action and Script to update Copyright Year for Source Files

[ParagEkbote]

What does this PR do?

Since ever year, updating the copyright dates for files has been manual, this PR introduces a gh-action and script which can be triggered once a year to update the date for all files. The gh-action will open a PR to update the dates instead of committing changes directly on main. Could you please review?

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Who can review?

@sayakpaul

[sayakpaul]

Thanks for starting it. Would it be possible to create a draft PR with this workflow and see if it's working as expected?

[sayakpaul]

Sometimes the Copyright starts with a different team name:

diffusers/src/diffusers/models/transformers/transformer_flux.py

Line 1 in a5a0ccf

# Copyright 2025 Black Forest Labs, The HuggingFace Team and The InstantX Team. All rights reserved.

[ParagEkbote]

I have covered this pattern as well. You can view it in this PR: https://github.com/ParagEkbote/diffusers/pull/1/files#diff-15d8601315be2c5bfcd65bf7c17764dda7c0a66190e5113974939d127390340d

[ParagEkbote]

I have tested the workflow in my fork and it's working correctly; you can view it here: ParagEkbote#1

Could you please review?

[sayakpaul]

I left some questions on that PR. I think changing the copyright year is quite simple to perform in an editor like VSCode and for that maintaining a workflow is likely an overkill.

[ParagEkbote]

I left some questions on that PR. I think changing the copyright year is quite simple to perform in an editor like VSCode and for that maintaining a workflow is likely an overkill.

It's meant to be a utility script that can be run to save time and since there are dates which are not updated from 2020, it can be useful. WDYT?

[JoeGaffney]

While automating copyright updates is convenient, updating all files every year will create a lot of Git history noise. Copyright is primarily relevant to when a file was created or significantly modified, so it might be cleaner to either keep the original year or use a range of years reflecting actual modifications. This would reduce unnecessary commits and keep Git history more meaningful.