fix: revert update dependency slash to v4 (#4118) (#4519)

This reverts commit 7a07f17.

Author: patak-dev

packages/plugin-vue/package.json

@@ -38,7 +38,7 @@
     "debug": "^4.3.2",
     "hash-sum": "^2.0.0",
     "rollup": "^2.38.5",
-    "slash": "^4.0.0",
+    "slash": "^3.0.0",
     "source-map": "^0.6.1"
   }
 }