Bump hotkeys-js from 3.9.3 to 3.9.4

Bumps [hotkeys-js](https://github.com/jaywcjlove/hotkeys) from 3.9.3 to 3.9.4.
- [Release notes](https://github.com/jaywcjlove/hotkeys/releases)
- [Commits](https://github.com/jaywcjlove/hotkeys/compare/v3.9.3...v3.9.4)

---
updated-dependencies:
- dependency-name: hotkeys-js
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

package.json

@@ -15,7 +15,7 @@
         "@fortawesome/vue-fontawesome": "^3.0.0-5",
         "buffer": "^6.0.3",
         "dompurify": "^2.3.8",
-        "hotkeys-js": "^3.9.3",
+        "hotkeys-js": "^3.9.4",
         "javascript-time-ago": "^2.5.2",
         "mux.js": "^6.0.1",
         "shaka-player": "4.0.1",