* Add pytest-cov; Remove code references to pip-tools and refactor method _build_package_list
* Regenerate lock file.
* Add back required typing-extensions, not sure how it got dropped from locking previously.
* Adopt the setup.cfg for coverage config.
* Actually pin to the version of click we have vendored in.
* Do not adopt coverage for CI since it slows everything down. Fix py36 dependency pinning.
* Drop support for 3.6 in this PR.
* No need to exclude the vendor and patched directory from the coverage reprot.
Oz N Tiram