Fix/v201

[RobertoPrevato]

• Fixes refresh_token endpoint should allow anonymous access explicitly #441 causing the refresh_token endpoint for OpenID Connect
  integrations to not work when an authenticated user is required by default.
• Fixes Incorrect handling of exceptions in websocket handlers #427, handling WebSocket errors according to ASGI specification.
• Fixes Mount problem  #443, raising a detailed exception when more than one application is
  sharing the same instance of Router
• Fixes Startup error #438 and A problem was encountered while booting on a domestic cpu #436, restoring support for uvicorn used programmatically
  and reloading the application object more than once in the same process.

[codecov-commenter]

Codecov Report

Attention: 19 lines in your changes are missing coverage. Please review.

Comparison is base (73b279c) 97.70% compared to head (e293776) 97.47%.

Files	Patch %	Lines
blacksheep/server/routing.py	65.62%	11 Missing ⚠️
blacksheep/server/application.py	53.33%	7 Missing ⚠️
blacksheep/server/websocket.py	80.00%	1 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #444      +/-   ##
==========================================
- Coverage   97.70%   97.47%   -0.24%     
==========================================
  Files          67       67              
  Lines        6278     6326      +48     
==========================================
+ Hits         6134     6166      +32     
- Misses        144      160      +16     

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