Bump acorn from 6.3.0 to 6.4.1 in /vuehr

Bumps [acorn](https://github.com/acornjs/acorn) from 6.3.0 to 6.4.1.
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](https://github.com/acornjs/acorn/compare/6.3.0...6.4.1)
Signed-off-by: Ndependabot[bot] <support@github.com>

vuehr/package-lock.json

@@ -1455,9 +1455,9 @@
       }
     },
     "acorn": {
-      "version": "6.3.0",
-      "resolved": "https://registry.npm.taobao.org/acorn/download/acorn-6.3.0.tgz",
-      "integrity": "sha1-AIdQkRn/pPwKAEHR6TpBfmjLhW4=",
+      "version": "6.4.1",
+      "resolved": "https://registry.npmjs.org/acorn/-/acorn-6.4.1.tgz",
+      "integrity": "sha512-ZVA9k326Nwrj3Cj9jlh3wGFutC2ZornPNARZwsNYqQYgN0EsV2d53w5RN/co65Ohn4sUAUtb1rSUAOD6XN9idA==",
       "dev": true
     },
     "acorn-walk": {