Log Message:
py-testtools: updated to 2.7.1

2.7.1

Improvements

* Remove various unused imports.
* Fix build backend. This should prevent version from being set to 0.0.0
  when building wheels.

2.7.0

Improvements

* Fix compatibility with Python 3.12.
* Add typing in various modules (still lacking full coverage).
* Drop the 'test' command for distutils. This has been
  deprecated since 2.6.0.
* Drop support for Python 3.6.