fix: silence dev/prod warning during sync (#13244)

Author: benmccann

.changeset/clever-phones-reply.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: silence dev/prod warning during sync

packages/kit/src/utils/routing.js

@@ -1,4 +1,5 @@
-import { BROWSER } from 'esm-env';
+// @ts-ignore - need to publish types for sub-package imports
+import BROWSER from 'esm-env/browser';
 
 const param_pattern = /^(\[)?(\.\.\.)?(\w+)(?:=(\w+))?(\])?$/;