Drop Symfony 5.x support on 3.2 branch (#976)

* Initial plan

* Drop Symfony 5.x support from all composer.json files

Co-authored-by: huangdijia <8337659+huangdijia@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: huangdijia <8337659+huangdijia@users.noreply.github.com>

Author: Copilot

composer.json

@@ -29,7 +29,7 @@
         "hyperf/macroable": "~3.2.0",
         "hyperf/support": "~3.2.0",
         "hyperf/tappable": "~3.2.0",
-        "symfony/var-dumper": "^5.3 || ^6.0 || ^7.0"
+        "symfony/var-dumper": "^6.0 || ^7.0"
     },
     "conflict": {
         "guzzlehttp/guzzle": "<7.0"