Add PHP 8.3 (#83)

Author: oittaa

.github/workflows/main.yml

@@ -18,7 +18,7 @@ jobs:
     - name: Setup PHP
       uses: shivammathur/setup-php@2.28.0
       with:
-        php-version: '8.2'
+        php-version: '8.3'
         tools: cs2pr, phpcs
     - name: Run phpcs
       run: phpcs -q --report=checkstyle src/ tests/ | cs2pr
@@ -27,7 +27,7 @@ jobs:
     runs-on: ubuntu-22.04
     strategy:
       matrix:
-        php-versions: ['8.1', '8.2']
+        php-versions: ['8.1', '8.2', '8.3']
     steps:
     - uses: actions/checkout@v4
     - name: Setup PHP
@@ -47,7 +47,7 @@ jobs:
     runs-on: ubuntu-22.04
     strategy:
       matrix:
-        php-versions: ['8.1', '8.2']
+        php-versions: ['8.1', '8.2', '8.3']
     steps:
     - uses: actions/checkout@v4
     - name: Setup PHP