Bump protobufjs from 6.10.2 to 6.11.4 in /webapp

Bumps [protobufjs](https://github.com/protobufjs/protobuf.js) from 6.10.2 to 6.11.4.
- [Release notes](https://github.com/protobufjs/protobuf.js/releases)
- [Changelog](https://github.com/protobufjs/protobuf.js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/protobufjs/protobuf.js/commits)

---
updated-dependencies:
- dependency-name: protobufjs
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

webapp/package.json

@@ -64,7 +64,7 @@
     "karma-coverage-istanbul-reporter": "^2.1.1",
     "karma-jasmine": "~2.0.1",
     "karma-jasmine-html-reporter": "^0.2.2",
-    "protobufjs": "^6.10.2",
+    "protobufjs": "^6.11.4",
     "protractor": "^7.0.0",
     "ts-node": "~7.0.0",
     "tslint": "~5.11.0",