Update tests.yml

Author: eiriksm

.github/workflows/tests.yml

@@ -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