CI: remove travis; fix wheel build in GH actions

Author: MuellerSeb

.github/workflows/main.yml

@@ -40,6 +40,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
+          pip install -U wheel
           pip install -r requirements_setup.txt
           pip install -r requirements.txt
           pip install -r requirements_test.txt