Update file(s) from wp-cli/.github

Author: schlessera

.github/workflows/testing.yml

@@ -87,6 +87,9 @@ jobs:
           - php: '8.0'
             wp: 'trunk'
             mysql: '5.6'
+          - php: '8.1'
+            wp: 'trunk'
+            mysql: '8.0'
           - php: '5.6'
             wp: '3.7'
             mysql: '5.6'