Pin GitHub Actions runners to a specific version (#73)

Author: ErikSchierboom

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ on:
 jobs:
   build:
     name: Tests
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     steps:
       - name: Checkout code
         uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11