Escape PHP 8.0 in integration test matrix item

Author: Jonathan Visser

.github/workflows/test.yaml

@@ -6,7 +6,7 @@ jobs:
   integration_test:
     strategy:
       matrix:
-        php_version: [8.0, 8.1, 8.2, 8.3, 8.4]
+        php_version: ['8.0', 8.1, 8.2, 8.3, 8.4]
         testsuite: [general, brancher]
     runs-on: ubuntu-latest
     steps: