Update main.yml

3.10 -> "3.10"

Author: mikaem

.github/workflows/main.yml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macOS-latest]
-        python-version: [3.7, 3.8, 3.9, 3.10]
+        python-version: ["3.7", "3.8", "3.9", "3.10"]
     name: Python ${{ matrix.python-version }} example
 
     steps: