bump min constraint for the ObjectMapper component

Author: xabbuh

composer.json

@@ -54,7 +54,7 @@
         "symfony/messenger": "^6.4|^7.0",
         "symfony/mime": "^6.4|^7.0",
         "symfony/notifier": "^6.4|^7.0",
-        "symfony/object-mapper": "^7.3",
+        "symfony/object-mapper": "^v7.3.0-beta2",
         "symfony/process": "^6.4|^7.0",
         "symfony/rate-limiter": "^6.4|^7.0",
         "symfony/scheduler": "^6.4.4|^7.0.4",