chore(deps): update devdependency @nuxtjs/pwa to v3

Author: renovate-bot

package.json

@@ -33,7 +33,7 @@
     "py-loader": "martim00/python-webpack-loader"
   },
   "devDependencies": {
-    "@nuxtjs/pwa": "^2.0.5",
+    "@nuxtjs/pwa": "^3.3.4",
     "codecov": "latest",
     "eslint": "^4.17.0",
     "eslint-config-standard": "latest",