install latest mercurial for tests

.github/workflows/test.yml

@@ -107,11 +107,9 @@ jobs:
           pip install --upgrade -r dev-requirements.txt
           python setup.py bdist_wheel
           pip install dist/*.whl
+          # add for mercurial tests
+          pip install mercurial hg-evolve
           pip freeze
-          # hg-evolve pinned to 9.2 because hg-evolve dropped support for
-          # hg 4.5, installed with apt in Ubuntu 18.04
-          $(hg debuginstall --template "{pythonexe}") -m pip install setuptools --user
-          $(hg debuginstall --template "{pythonexe}") -m pip install hg-evolve==9.2 --user
 
       - name: "Run tests"
         run: |