fix: package.json & package-lock.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-NPM-537603
- https://snyk.io/vuln/SNYK-JS-NPM-537604
- https://snyk.io/vuln/SNYK-JS-NPM-537606

Author: snyk-bot

package-lock.json

@@ -31,7 +31,7 @@
   },
   "homepage": "https://github.com/jrtnq514/vue-user-timeout#readme",
   "dependencies": {
-    "npm": "^6.13.1",
+    "npm": "^6.13.4",
     "snyk": "^1.248.0"
   },
   "devDependencies": {