AAI-251 Better caching of RSA keys

[marius-mather]

Description

AAI-251: while working on this PR I realized a lot of the slowness of our endpoints came from fetching the signing keys from Auth0 on every request. I added some basic caching for them which seems to help a lot, but this PR improves it so that we refresh the signing keys after 30 minutes, and allow for a retry on failure in case the cache is out of date.

Changes

• Add cachetools so we can use a time-based cache
• Cache RSA signing keys for half an hour
• Unit tests

Checklist

• I have commented my code, particularly in hard-to-understand areas
• I have added unit / integration tests that prove my fix is effective or that my feature works
• I have run all tests locally and they pass
• I have updated the documentation (if applicable)

How to Test Manually (if necessary)

Run uv run pytest

[amandazhuyilan]

Wow! Thanks for the improvement!