feat: make TimeoutError extend builtins.TimeoutError

[danphenderson]

Addressing issue #1495.

Note, depending on the Python implementation __builtins__ references either the module builtins or the dictionary builtins.__dict__. (Ref). Therefore, I am importing TimeoutError as TimeOutErrorBuiltin from builtins to account for this implementation detail.

Additionally, I modified .gitignore to ignore Pipenv artifacts.

[danphenderson]

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[mxschmitt]

Thank you for your contribution, lets add a test for it?

e.g. a small one after here.

[danphenderson]

Good idea! Thank you for the feedback.