Workflow: Make sure wheel is installed

Author: foosel

.github/workflows/publish-to-test-pypi.yml

@@ -11,6 +11,9 @@ jobs:
         uses: actions/setup-python@v1
         with:
           python-version: 3.7
+      - name: Install build dependencies
+        run: >-
+          python -m pip install wheel --user
       - name: 🔨 Build a binary wheel and a source tarball
         run: >-
           python setup.py sdist bdist_wheel