Fix warning CA1062#CacheSyntax

[Zombach]

Pull Request

The issue or feature being addressed

#2215

Details on the issue fix or feature implementation

• Suppress CA1062 in src/Polly/Caching/CacheSyntax.cs or fix the warning

Confirm the following

• I started this PR by branching from the head of the default branch
• I have targeted the PR to merge into the default branch
• I have included unit tests for the issue/feature

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.69%. Comparing base (72331dc) to head (92e5d10).
Report is 11 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2240      +/-   ##
==========================================
- Coverage   84.00%   83.69%   -0.32%     
==========================================
  Files         313      313              
  Lines        7227     7402     +175     
  Branches     1078     1114      +36     
==========================================
+ Hits         6071     6195     +124     
- Misses        785      828      +43     
- Partials      371      379       +8     

Flag	Coverage Δ
linux	83.69% <100.00%> (-0.32%)	⬇️
macos	83.69% <100.00%> (-0.32%)	⬇️
windows	?

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