litellm - 💡(How to fix) Fix Preserve original PR authorship when squashing staging branches into main

Hi @Sameerlite, thanks for merging my recent PRs.

I noticed that when a dated staging branch is squashed into main, the original PR authors are kept only as Co-authored-by: trailers and the commit author becomes the maintainer who runs the squash. GitHub's contributors graph and the README contrib.rocks image are author-only, so contributors whose work ships this way never appear there even though their code is in main.

For reference, here are my merged PRs and the main commits that shipped them (I am credited as co-author on each):

• #28567 jp. Bedrock cross-region opus-4-7 -> shipped in d671a09c20 (Litellm oss staging 050626)
• #28575 forward custom_llm_provider through the Responses bridge -> d671a09c20
• #27831 jp. Bedrock cross-region sonnet-4-6 -> d671a09c20
• #28572 EU/AU/JP Bedrock Anthropic 1hr cache pricing -> c7ab9adde5 (Litellm oss staging 030626)
• #28569 Vertex AI Anthropic 1hr cache tier -> c7ab9adde5
• #28151 UI pause/resume switch on the models table -> b84f7f82f7
• #27927 blocked flag for model pause/resume -> 492891cad8
• #27832 sanitize empty text blocks on /v1/messages -> f35e7eb2f6
• #28573 us-gov Sonnet 4.5 200k-tier pricing fix
• #28574 us-gov Haiku 4.5 1hr cache write pricing

Would you consider either of these so original authors get proper credit:

1. Preserve per-PR authorship when rolling staging into main, for example merge instead of re-squash, or set the squash author to the PR author, or
2. Enable the all-contributors bot so contributors can be added to the README list.

Happy to send a PR for option 2 setup if that is useful. Thanks for considering it.