Fix warning CA1062#AsyncCacheSyntax

[Zombach]

Pull Request

The issue or feature being addressed

#2215

Details on the issue fix or feature implementation

• Suppress CA1062 in src/Polly/Caching/AsyncCacheSyntax.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 84.35%. Comparing base (72331dc) to head (079cba5).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2242      +/-   ##
==========================================
+ Coverage   84.00%   84.35%   +0.34%     
==========================================
  Files         313      313              
  Lines        7227     7248      +21     
  Branches     1078     1081       +3     
==========================================
+ Hits         6071     6114      +43     
+ Misses        785      771      -14     
+ Partials      371      363       -8     

Flag	Coverage Δ
linux	84.35% <100.00%> (+0.34%)	⬆️
macos	84.35% <100.00%> (+0.34%)	⬆️
windows	84.35% <100.00%> (+0.34%)	⬆️

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