Bump braces, watchpack and webpack-dev-server in /web_src

Bumps [braces](https://github.com/micromatch/braces) to 3.0.3 and updates ancestor dependencies [braces](https://github.com/micromatch/braces), [watchpack](https://github.com/webpack/watchpack) and [webpack-dev-server](https://github.com/webpack/webpack-dev-server). These dependencies need to be updated together.


Updates `braces` from 2.3.1 to 3.0.3
- [Changelog](https://github.com/micromatch/braces/blob/master/CHANGELOG.md)
- [Commits](https://github.com/micromatch/braces/compare/2.3.1...3.0.3)

Updates `watchpack` from 1.5.0 to 1.7.5
- [Release notes](https://github.com/webpack/watchpack/releases)
- [Commits](https://github.com/webpack/watchpack/compare/v1.5.0...v1.7.5)

Updates `webpack-dev-server` from 2.11.2 to 5.0.4
- [Release notes](https://github.com/webpack/webpack-dev-server/releases)
- [Changelog](https://github.com/webpack/webpack-dev-server/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack/webpack-dev-server/compare/v2.11.2...v5.0.4)

---
updated-dependencies:
- dependency-name: braces
  dependency-type: indirect
- dependency-name: watchpack
  dependency-type: indirect
- dependency-name: webpack-dev-server
  dependency-type: direct:development
...

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

web_src/package.json

@@ -56,6 +56,6 @@
     "vue-template-compiler": "2.5.16",
     "vuex": "3.0.1",
     "webpack": "3.11.0",
-    "webpack-dev-server": "2.11.2"
+    "webpack-dev-server": "5.0.4"
   }
 }