test: use py3{py-minor-version} format rather than py3.{py-minor-version} for testenv name

This convention is more "tox-friendly", since an environment with 'py$MAJOR$MINOR'
in its name will use the Python interpreter at version $MAJOR.MINOR as base python.

In particular, in this way, we could avoid the repetition of different testenv
configurations which only differ by the basepython variable.

This change required a workaround in the GitHub Actions workflow configuration,
since the Python version there has a dot that separates major and minor versions.

Author: marcofavorito

.github/workflows/test.yml

@@ -26,6 +26,7 @@ jobs:
       run:  pip install tox
     - name: Unit tests and coverage
       run: |
+        pyver=`echo ${{ matrix.python-version }} | tr -d "."`
         tox -e py${{ matrix.python-version }}
     - name: Upload coverage to Codecov
       uses: codecov/codecov-action@v1

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = check-copyright, black-check, isort-check, docs, flake8, mypy, py3.8, py3.7
+envlist = check-copyright, black-check, isort-check, docs, flake8, mypy, py3{7,8,9,10}
 
 [testenv]
 setenv =
@@ -19,11 +19,9 @@ commands =
         --cov-report=html \
         --cov-report=term
 
-[testenv:py3.7]
-basepython = python3.7
-
-[testenv:py3.8]
-basepython = python3.8
+[testenv:py{37,38,39,310}]
+commands =
+    {[testenv]commands}
 
 [testenv:flake8]
 skip_install = True