Bump qs from 6.8.0 to 6.9.0 in /vuejs

Bumps [qs](https://github.com/ljharb/qs) from 6.8.0 to 6.9.0.
- [Release notes](https://github.com/ljharb/qs/releases)
- [Changelog](https://github.com/ljharb/qs/blob/master/CHANGELOG.md)
- [Commits](https://github.com/ljharb/qs/compare/v6.8.0...v6.9.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

vuejs/package.json

@@ -14,7 +14,7 @@
     "core-js": "^2.6.5",
     "postcss-import": "^12.0.1",
     "postcss-nested": "^4.1.2",
-    "qs": "^6.8.0",
+    "qs": "^6.9.0",
     "tailwindcss": "^1.1.2",
     "vue": "^2.6.10",
     "vue-router": "^3.1.3",