Test lowest on PHP 8.0 too

Author: GrahamCampbell

.github/workflows/tests.yml

@@ -43,7 +43,7 @@ jobs:
 
     strategy:
       matrix:
-        php: ['7.1', '7.2', '7.3', '7.4']
+        php: ['7.1', '7.2', '7.3', '7.4', '8.0']
 
     steps:
       - name: Checkout Code