Fix #421

[RobertoPrevato]

• Fixes Handled exception is logged as unhandled #421 reported by @mohd-akram, causing handled exceptions to be logged like unhandled, when defining exception handlers using subclasses.
• Removes wrong type annotations in two functions in blacksheep.utils.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (fc9e82d) 97.46% compared to head (0bf03f5) 97.48%.

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #458      +/-   ##
==========================================
+ Coverage   97.46%   97.48%   +0.01%     
==========================================
  Files          67       67              
  Lines        6363     6363              
==========================================
+ Hits         6202     6203       +1     
+ Misses        161      160       -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.