ci: add uv package install cooldown

[bhimrazy]

What does this PR do?

Adds a CI-only supply-chain guard for uv-based workflows: the resolver refuses PyPI releases published within the last 2 days, reducing the chance that newly uploaded typosquats or malicious packages land in CI before they are detected/yanked.

ref: Lightning-AI/pytorch-lightning#21722.

Env var	Value	Scope
UV_EXCLUDE_NEWER	"2 days"	uv-based workflow jobs

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84%. Comparing base (e5cebd0) to head (35514d1).
⚠️ Report is 1 commits behind head on main.
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Additional details and impacted files

@@         Coverage Diff         @@
##           main   #157   +/-   ##
===================================
  Coverage    84%    84%           
===================================
  Files        12     12           
  Lines       517    517           
===================================
  Hits        436    436           
  Misses       81     81           

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