Update master php testing versions

Signed-off-by: Joas Schilling <coding@schilljs.com>

Author: nickvergessen

.github/workflows/lint-php.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php-versions: ["7.4", "8.0"]
+        php-versions: ["7.4", "8.0", "8.1"]
 
     name: php-lint
 

.github/workflows/phpunit.yml

@@ -87,7 +87,7 @@ jobs:
       # do not stop on another job's failure
       fail-fast: false
       matrix:
-        php-versions: ['7.4', '8.0']
+        php-versions: ['7.4', '8.0', "8.1"]
         databases: ['mysql']
         server-versions: ['master']