Switch tox-github-action from master to main branch

Author: frenzymadness

.github/workflows/tox-fedora.yml

@@ -8,7 +8,7 @@ jobs:
     steps:
     - uses: actions/checkout@v2
     - name: Run Tox tests
-      uses: fedora-python/tox-github-action@master
+      uses: fedora-python/tox-github-action@main
       with:
         tox_env: ${{ matrix.tox_env }}
         dnf_install: >