fix(server): do not block connection handler task during client auth

[M0dEx]

This PR fixes #34, where a malicious client could block the connection handler task by delaying client authentication.

[codecov]

Codecov Report

Attention: 13 lines in your changes are missing coverage. Please review.

Comparison is base (13e7f48) 70.01% compared to head (95739bd) 71.40%.

Files	Patch %	Lines
src/server/connection.rs	59.37%	13 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #35      +/-   ##
==========================================
+ Coverage   70.01%   71.40%   +1.38%     
==========================================
  Files          19       19              
  Lines        1004     1014      +10     
==========================================
+ Hits          703      724      +21     
+ Misses        301      290      -11     

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