Added pytest-cov and addressed outdated references to pip-tools (#5038)

* 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.

.github/workflows/ci.yaml

@@ -39,9 +39,6 @@ jobs:
       matrix:
         python-version: [3.7, 3.8, 3.9, "3.10"]
         os: [MacOS, Ubuntu, Windows]
-        include:
-          - python-version: 3.6
-            os: Ubuntu
 
     steps:
       - uses: actions/checkout@v1
@@ -89,7 +86,7 @@ jobs:
           PYTHONIOENCODING: "utf-8"
           GIT_SSH_COMMAND: ssh -o StrictHostKeyChecking=accept-new -o CheckHostIP=no
         run: |
-          pipenv run pytest -ra -n auto --fulltrace tests
+          pipenv run pytest -ra -n auto -v --fulltrace tests
 
   build:
     name: Build Package