Merge pull request #6 from cesargb/php81

tests to php81

Author: cesargb

.github/workflows/tests.yml

@@ -8,7 +8,7 @@ jobs:
         strategy:
             fail-fast: false
             matrix:
-                php: [7.4, 8.0]
+                php: [7.4, 8.0, 8.1]
 
         name: P${{ matrix.php }}