add support for providing a custom requests.Session in client

[syphar]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (b5ead78) 87.31% compared to head (51915ea) 87.32%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #39      +/-   ##
==========================================
+ Coverage   87.31%   87.32%   +0.01%     
==========================================
  Files           7        7              
  Lines         946      947       +1     
==========================================
+ Hits          826      827       +1     
  Misses        120      120              

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[syphar]

@klamann we found that this feature would have helped us writing cleaner code.

In our case we wanted retries for HTTP requests, and with the option to hand in a custom session this would have worked more easily.

Another usecase I can imagine for this would be proxies.

If the general feature is fine with you, I'll do tests & changelog.

[klamann]

I like the idea, and the change seems to be simple enough. I'm willing to merge this if you add a test case and changelog entry.

[syphar]

@klamann I updated the changelog, and added a short test with a custom session.

[klamann]

sorry for the deplay; merging!