fix(debug): Take into account parent handlers for debug logger

[sentrivana]

We only check logger.handlers for existing handlers. This ignores any potential parent handlers. By using hasHandlers() (docs) instead we take those into account as well.

Closes #3944

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 79.56%. Comparing base (4f51ff3) to head (d5c72fa).
Report is 1 commits behind head on master.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
sentry_sdk/debug.py	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4133   +/-   ##
=======================================
  Coverage   79.56%   79.56%           
=======================================
  Files         140      140           
  Lines       15636    15636           
  Branches     2652     2652           
=======================================
  Hits        12441    12441           
  Misses       2362     2362           
  Partials      833      833           

Files with missing lines	Coverage Δ
sentry_sdk/debug.py	91.30% <0.00%> (ø)