Remove Python 2 pip. Ref #795. (#796)

Author: jaraco

.github/workflows/python-tests.yml

@@ -69,10 +69,7 @@ jobs:
       - run: pip install -U 'setuptools>=45'
         if: matrix.python_version != 'msys2'
       - run: pip install -e .[toml,test]
-      # pip2 is needed because Mercurial uses python2 on Ubuntu 20.04
       - run: |
-          curl https://bootstrap.pypa.io/pip/2.7/get-pip.py --output get-pip.py
-          sudo python2 get-pip.py
           $(hg debuginstall --template "{pythonexe}") -m pip install hg-git --user
         if: matrix.os == 'ubuntu-latest'
       - run: pytest