upgrade to nextjs 15.3.2 (#5268)

reflex/constants/installer.py

@@ -75,7 +75,7 @@ fetch-retries=0
 
 
 def _determine_nextjs_version() -> str:
-    default_version = "15.3.1"
+    default_version = "15.3.2"
     if (version := os.getenv("NEXTJS_VERSION")) and version != default_version:
         from reflex.utils import console