chore(deps) updated flagsmith/flagsmith-php-client for FlagsmithProvider

Signed-off-by: Chris Lightfoot-Wild <github-clw@wild.me.uk>

Author: ChrisLightfootWild

providers/Flagsmith/composer.json

@@ -22,8 +22,7 @@
   ],
   "require": {
     "php": "^8.1",
-    "ext-json": "*",
-    "flagsmith/flagsmith-php-client": "^4.1",
+    "flagsmith/flagsmith-php-client": "^4.5.1",
     "open-feature/sdk": "^2.0"
   },
   "require-dev": {