chore(ci): Add PHP 8.3 (#24)

Author: GermanCoding

.github/workflows/tests.yml

@@ -12,7 +12,7 @@ jobs:
         strategy:
             fail-fast: false
             matrix:
-                php-version: ["5.4", "5.5", "5.6", "7.1", "7.2", "7.3", "7.4", "8.0", "8.1", "8.2"]
+                php-version: ["5.4", "5.5", "5.6", "7.1", "7.2", "7.3", "7.4", "8.0", "8.1", "8.2", "8.3"]
                 experimental: [false]
                 composer-options: ['']
                 include: