Update vue monorepo to v2.7.15

Author: renovate[bot]

app/package.json

@@ -15,7 +15,7 @@
     "moment-timezone": "0.5.33",
     "parse-torrent": "9.1.3",
     "register-service-worker": "1.7.2",
-    "vue": "2.6.12",
+    "vue": "2.7.15",
     "vue-i18n": "9.1.4",
     "vue-plyr": "7.0.0",
     "vue-promised": "2.0.3",
@@ -32,7 +32,7 @@
     "sass": "1.32.11",
     "sass-loader": "11.0.1",
     "vue-cli-plugin-vuetify": "2.3.1",
-    "vue-template-compiler": "2.6.12",
+    "vue-template-compiler": "2.7.15",
     "vuetify-loader": "1.7.2"
   }
 }