15200 - Improve Script for Detecting Snips Requiring PR Tests

[mike-weiner]

Description

Closes #15200.

This PR refactors scripts/pr_tests.py to instead use the files changed portion of a PR to determine which snips require testing.

Proof of Testing

@craigbox left some examples in #15200 of where problems were encountered. I used those as my testing for the updates to this script.

For folks that want to test, installing uv is straightforward and makes the dependency management of Python much easier. Installation instructions are here.

Correctly found all snips requiring testing in a PR:

weiner istio.io (master) % uv run --with PyGithub ./scripts/pr_tests.py --token= 15168
ambient/getting-started,ambient/getting-started/cleanup,ambient/getting-started/deploy-sample-app,ambient/getting-started/enforce-auth-policies,ambient/getting-started/manage-traffic,ambient/getting-started/secure-and-visualize,ambient/getting-started/setup,ambient/usage/extend-waypoint-wasm

Correctly did not test snips being removed in a PR:

weiner istio.io (master) % uv run --with PyGithub ./scripts/pr_tests.py --token= 15227
NONE

Reviewers

• Ambient
• Docs
• Installation
• Networking
• Performance and Scalability
• Extensions and Telemetry
• Security
• Test and Release
• User Experience
• Developer Infrastructure
• Localization/Translation

[mike-weiner]

@craigbox - I think this PR just got buried and lost in the shuffle. Can you re-add this one to your review list? Thanks!

[craigbox]

I'm not actually working on Istio at present sorry; I'm away with my family. I'll have a look when time permits but that is unlikely to be until November.

[mike-weiner]

No worries! Sorry for the pester. Enjoy the time away with the family!