Quote all versions in ci.yml

Author: j4mie

.github/workflows/ci.yml

@@ -9,13 +9,13 @@ jobs:
 
     strategy:
       matrix:
-        python: [3.6, 3.7, 3.8, 3.9, "3.10"]
-        django: [3.2, 4.0]
+        python: ["3.6", "3.7", "3.8", "3.9", "3.10"]
+        django: ["3.2", "4.0"]
         exclude:
-          - python: 3.6
-            django: 4.0
-          - python: 3.7
-            django: 4.0
+          - python: "3.6"
+            django: "4.0"
+          - python: "3.7"
+            django: "4.0"
         database_url:
           - postgres://runner:password@localhost/project
           - mysql://root:[email protected]/project