ui: remove PWA support

We're not using it at the moment.

Author: sevein

ui/package.json

@@ -12,7 +12,6 @@
     "bootstrap": "^4.3.1",
     "bootstrap-vue": "^2.0.3",
     "core-js": "^2.6.5",
-    "register-service-worker": "^1.6.2",
     "vue": "^2.6.10",
     "vue-class-component": "^7.0.2",
     "vue-property-decorator": "^8.1.0",
@@ -22,7 +21,6 @@
   "devDependencies": {
     "@types/jest": "^23.1.4",
     "@vue/cli-plugin-babel": "^3.11.0",
-    "@vue/cli-plugin-pwa": "^3.11.0",
     "@vue/cli-plugin-typescript": "^3.11.0",
     "@vue/cli-plugin-unit-jest": "^3.11.0",
     "@vue/cli-service": "^3.11.0",