fix(ci): resolve webhook IP cache invalidation bug

[MrButtCode]

[FIX] resolve webhook IP cache invalidation bug

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Resolves a critical performance bug in the webhook IP validation logic.

In utility.py the cached_load_time variable was declared locally strictly inside cache_has_expired(). This caused the timestamp to reset to the 1970 epoch on every single function call. As a result the expiration check always evaluated to True forcing the application to make a syncronous HTTP request to the GitHub API on every incoming webhook instead of using the cached IP blocks.

The Fix:
Elevated cached_load_time to module level scope and updated get_cached_web_hook_blocks() to reset the timestamp to datetime.now() only after a successful GitHub API fetch. This restores the intended 1 hour caching behavior and prevents unnecesary rate limited API calls.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[canihavesomecoffee]

While the fix looks ok to me, all these changes don't. Imports should not be in functions unless there's no other choice, and exceptions for unit tests definitely don't belong in here. I'd rather have a bit bigger PR change (i.e. making the cached_load_time an argument you can pass to the function) rather than these "bypasses".