Add tests to show that the excess turns are discarded when creating the readable tracker

[varunshankar]

Proposed changes:

• Add tests to show that the excess turns are discarded when creating the readable tracker (without specifying the max_turns arg)

Status (please check what you already did):

• added some tests for the functionality
• updated the documentation
• updated the changelog (please check changelog for instructions)
• reformat files using black (please check Readme for instructions)

[twerkmeister]

That looks already pretty good. However, I would suggest adding the max turns and also the other default arguments explicitly to call of tracker_as_readable_transcript in the test. We want to test that the method does what we think it does. Right now, we also test that the default arguments have specific values and the test is gonna break if that default changes, although the method might still be perfectly fine