tests: php 8.3 support

Author: tpetry

.github/workflows/phpunit.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php: [8.0, 8.1, 8.2]
+        php: [8.0, 8.1, 8.2, 8.3]
         laravel: [6.*, 7.*, 8.*, 9.*, 10.*]
         stability: [prefer-lowest, prefer-stable]
         include:
@@ -44,6 +44,16 @@ jobs:
           - php: 8.2
             laravel: 9.*
             stability: prefer-lowest
+          - php: 8.3
+            laravel: 6.*
+          - php: 8.3
+            laravel: 7.*
+          - php: 8.3
+            laravel: 8.*
+            stability: prefer-lowest
+          - php: 8.3
+            laravel: 9.*
+            stability: prefer-lowest
 
     name: P${{ matrix.php }} - L${{ matrix.laravel }} - ${{ matrix.stability }}