ci: add diff command

[masci]

Related Issues

• fixes the problem of not knowing if an integration has changes in main that were not released yet.

Proposed Changes:

Add a ./show_unreleased.sh command at the root of the repo that will:

• show the diff of the changes that were not yet released
• show nothing if the integration has no changes in main that need to be released

How did you test it?

Manually tested on a bunch of integrations, e.g.:

./show_unreleased.sh chroma
-> no output, means all good

Notes for the reviewer

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.