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

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-VUE-8219889

Author: snyk-bot

package-lock.json

@@ -15,10 +15,10 @@
     "core-js": "^2.6.5",
     "element-ui": "^2.11.1",
     "lodash": "^4.17.14",
-    "vue": "^2.6.10",
+    "vue": "^3.0.0",
     "vue-class-component": "^7.0.2",
     "vue-perfect-scrollbar": "^0.1.0",
-    "vue-property-decorator": "^8.1.0",
+    "vue-property-decorator": "^8.2.2",
     "vue-router": "^3.0.3",
     "vuex": "^3.0.1",
     "vuex-class": "^0.3.2",