Add support for PEP 604

[RobertoPrevato]

No description provided.

[codecov-commenter]

Codecov Report

Merging #261 (c365b1a) into main (5eb5d17) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main      #261   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           59        59           
  Lines         5625      5643   +18     
=========================================
+ Hits          5625      5643   +18     

Impacted Files	Coverage Δ
blacksheep/server/normalization.py	100.00% <100.00%> (ø)
blacksheep/server/openapi/v3.py	100.00% <100.00%> (ø)

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