[PHP]: Update symfony/form requirement

---
updated-dependencies:
- dependency-name: symfony/form
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

composer.json

@@ -21,7 +21,7 @@
         "doctrine/orm": "^2.5",
         "serendipity_hq/component-array-writer": "^5.1 || ^6.0",
         "serendipity_hq/component-value-objects": "^7.1",
-        "symfony/form": "^4.4|^5.4|^6.0",
+        "symfony/form": "^4.4|^5.4|^6.0|^7.0",
         "symfony/framework-bundle": "^4.4|^5.4|^6.0|^7.0",
         "symfony/options-resolver": "^4.4|^5.4|^6.0",
         "symfony/routing": "^4.4|^5.4|^6.0",