Ensure OIDC Callback Server releases bound TCP port

[Andy-Grigg]

Closes #137

The OIDCCallbackHTTPServer wasn't correctly releasing TCP port 32284. This caused problems if we tried to authenticate to a second OIDC server in the same script, e.g. by using the STK.

This PR re-works the OIDCCallbackHTTPServer implementation to use handle_request() instead of serve_forever(), which seems to eliminate the need to run the server in a separate thread. Instead, we now synchronously wait the login_timeout length of time for the server to handle a request. If it does, we return the auth_code.

I have also added tests that check the status of the TCP port both when the server is running and when it has been closed.

[codecov]

Codecov Report

Merging #138 (5a1f8ea) into main (8ba5ec2) will increase coverage by 0.18%.
The diff coverage is 27.27%.

@@            Coverage Diff             @@
##             main     #138      +/-   ##
==========================================
+ Coverage   91.65%   91.83%   +0.18%     
==========================================
  Files           8        8              
  Lines         827      821       -6     
==========================================
- Hits          758      754       -4     
+ Misses         69       67       -2     

Impacted Files	Coverage Δ
src/ansys/openapi/common/_oidc.py	74.49% <11.11%> (+1.16%)	⬆️
src/ansys/openapi/common/_util.py	99.44% <100.00%> (-0.02%)	⬇️

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[Andy-Grigg]

Will probably be superseded by #139

We have decided to merge this fix for the upcoming 1.0.0 release. #139 will be merged following the release.

[da1910]

This all looks OK, the test is a nice touch!

[Andy-Grigg]

We are aware that the coverage in this code area is sub-optimal. #139 will resolve this