Test on PHP 8.4

* Add 8.4 to matrix

.github/workflows/tests.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php: ['7.1', '7.2', '7.3', '7.4', '8.0', '8.1', '8.2', '8.3']
+        php: ['7.1', '7.2', '7.3', '7.4', '8.0', '8.1', '8.2', '8.3', '8.4']
 
     steps:
       - name: Checkout code
@@ -25,6 +25,10 @@ jobs:
           tools: composer:v2
           coverage: none
 
+      - name: Emulate PHP 8.3
+        run: composer config platform.php 8.3.999
+        if: matrix.php == '8.4'
+
       - name: Install PHP dependencies
         run: composer update --prefer-dist --no-interaction --no-progress