actions: use ubuntu-22.04 image

Author: dktapps

.github/workflows/main.yml

@@ -12,7 +12,7 @@ jobs:
       matrix:
         php: ["8.1", "8.2", "8.3", "8.4"]
     name: PHP ${{ matrix.php }}
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v4