Set up check-manifest and check-python-versions on CI

.github/workflows/build.yml

@@ -76,6 +76,8 @@ jobs:
         toxenv:
           - flake8
           - isort
+          - check-manifest
+          - check-python-versions
 
     steps:
       - name: Git clone

tox.ini

@@ -24,3 +24,13 @@ commands = flake8 findimports.py setup.py tests.py testsuite.py
 deps = isort
 skip_install = true
 commands = isort {posargs: -c --diff findimports.py setup.py tests.py testsuite.py}
+
+[testenv:check-manifest]
+deps = check-manifest
+skip_install = true
+commands = check-manifest {posargs}
+
+[testenv:check-python-versions]
+deps = check-python-versions
+skip_install = true
+commands = check-python-versions {posargs}