Add Symfony 7.3 build

Author: mbabker

.github/workflows/run-tests.yml

@@ -10,7 +10,7 @@ jobs:
       fail-fast: true
       matrix:
         php: ['8.3', '8.4']
-        symfony: ['6.4.*', '7.2.*']
+        symfony: ['6.4.*', '7.2.*', '7.3.*@beta']
         composer-flags: ['--prefer-stable']
         can-fail: [false]
         include: