sprinkle in pip install of setuptools_scm to avoid the setuptools bug

Author: RonnyPfannschmidt

.github/workflows/main.yml

@@ -94,10 +94,10 @@ jobs:
       uses: actions/setup-python@v2
       with:
         python-version: ${{ matrix.python }}
-    - name: Install tox
+    - name: Install tox setuptools_scm
       run: |
         python -m pip install --upgrade pip
-        pip install tox
+        pip install tox setuptools_scm
     - name: Test
       run: |
         tox -e ${{ matrix.tox_env }}

tox.ini

@@ -3,6 +3,7 @@ envlist=py27,py37,docs,linting
 
 [testenv]
 deps=
+    setuptools_scm
     pytest
     pytest-timeout
 passenv = GITHUB_ACTIONS