Bump em-websocket from 0.5.2 to 0.5.3 (#2229)

Bumps [em-websocket](https://github.com/igrigorik/em-websocket) from 0.5.2 to 0.5.3.
- [Release notes](https://github.com/igrigorik/em-websocket/releases)
- [Changelog](https://github.com/igrigorik/em-websocket/blob/master/CHANGELOG.rdoc)
- [Commits](https://github.com/igrigorik/em-websocket/compare/v0.5.2...v0.5.3)

---
updated-dependencies:
- dependency-name: em-websocket
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile.lock

@@ -48,9 +48,9 @@ GEM
     diff-lcs (1.4.4)
     domain_name (0.5.20190701)
       unf (>= 0.0.5, < 1.0.0)
-    em-websocket (0.5.2)
+    em-websocket (0.5.3)
       eventmachine (>= 0.12.9)
-      http_parser.rb (~> 0.6.0)
+      http_parser.rb (~> 0)
     equalizer (0.0.11)
     erubis (2.7.0)
     espeak-ruby (1.0.4)