DEP Update constraint for vendor-plugin

It's not strictly necessary since this is a dependency of
silverstripe/framework, but IMO it's good practice for projects to have
a reference to vendor-plugin, since the `composer vendor-expose` command
is specifically intended for use by projects.

composer.json

@@ -6,7 +6,7 @@
     "require": {
         "php": "^8.3",
         "silverstripe/recipe-plugin": "2.0.x-dev",
-        "silverstripe/vendor-plugin": "2.0.x-dev",
+        "silverstripe/vendor-plugin": "3.0.x-dev",
         "silverstripe/recipe-cms": "6.0.x-dev",
         "silverstripe-themes/simple": "3.3.x-dev",
         "silverstripe/login-forms": "6.0.x-dev"
@@ -35,4 +35,4 @@
     },
     "prefer-stable": true,
     "minimum-stability": "dev"
-}
+}