quotes around 3.10

Author: adrn

.github/workflows/tests.yml

@@ -25,7 +25,7 @@ jobs:
 
           - name: Python 3.10 with minimal dependencies and coverage
             os: ubuntu-latest
-            python: 3.10
+            python: '3.10'
             toxenv: py310-test-cov
 
           - name: Python 3.9