Checkpoint 1.3 backwards compatibility

[AleHD]

This pull request introduces three main additions:

• [x] 1.3 weights are now backwards compatible, meaning we can load checkpoints that had the .safetensors suffix incorrectly placed.
• [x] The logic used to get the filenames of weights shards was moved from serialize.weights.load_weights to serialize.utils.get_path thanks to the addition of return_all_matches keyword.
• [x] Addition of a test that verifies the capability to load weights when changing parallelism topology.

[zzhhjjj]

Hello,

Thank you for your PR.

As I understand it, you are verifying the checkpoint version. If it is 1.3, a different pattern will be used to retrieve the shards; otherwise, the existing pattern will be used. I suspect that this approach may not resolve all the issues, given that the checkpoint version 1.3 was only added to the main branch 4 days ago (see commit), whereas the bug was introduced a month and a half ago in this commit. Additionally, checking for version 1.2 seems problematic as it might disrupt the loading logic for all checkpoints before this commit.

Timeline: Checkpoint version=1.2 -> bug introduced -> Checkpoint version=1.3

We have already merged a quick fix that utilized a script to modify the file name: PR #151. Could you build upon this solution? Perhaps making it automatic when this pattern is detected, instead of requiring users to run the script manually.

I really appreciate your contribution.

[AleHD]

Thanks for the feedback. I implemented the suggested changes and tested it locally. Seems to be working ok. Let me know if you have any other comments.