Run 8.0 tests on Ubuntu 20.04

Author: Sephster

.github/workflows/tests.yml

@@ -8,13 +8,17 @@ on:
 
 jobs:
   tests:
-    runs-on: ubuntu-latest
-
     strategy:
       fail-fast: false
       matrix:
-        php: [8.0, 8.1, 8.2]
+        php: [8.1, 8.2]
+        os: [ubuntu-22.04]
         stability: [prefer-lowest, prefer-stable]
+        include:
+          - os: ubuntu-20.04
+            php: 8.0
+
+    runs-on: ${{ matrix.os }}
 
     name: PHP ${{ matrix.php }} - ${{ matrix.stability }}