chore(package): update vue to version 2.6.6

Author: greenkeeper[bot]

package.json

@@ -69,7 +69,7 @@
     "select2": "^4.0.6-rc.1",
     "select2-bootstrap4-theme": "^1.0.0",
     "simple-line-icons": "^2.4.1",
-    "vue": "^2.5.21",
+    "vue": "^2.6.6",
     "vue-chartjs": "^3.4.0",
     "vue-loading-spinner": "^1.0.11",
     "vue-notification": "^1.3.14",