Fix jinja template syntax in main.yaml

Author: dalito

template/.github/workflows/main.yaml.jinja

@@ -22,7 +22,7 @@ jobs:
         with:
           persist-credentials: false
 
-      - name: Set up Python {{ matrix.python-version }}
+      - name: Set up Python ${{ "{{" }} matrix.python-version {{ "}}" }}
         uses: actions/setup-python@0b93645e9fea7318ecaed2b359559ac225c90a2b
         with:
           python-version: ${{ "{{" }} matrix.python-version {{ "}}" }}