Bump shelljs and jshint (#81)

Removes [shelljs](https://github.com/shelljs/shelljs). It's no longer used after updating ancestor dependency [jshint](https://github.com/jshint/jshint). These dependencies need to be updated together.


Removes `shelljs`

Updates `jshint` from 2.11.0 to 2.13.6
- [Release notes](https://github.com/jshint/jshint/releases)
- [Changelog](https://github.com/jshint/jshint/blob/main/CHANGELOG.md)
- [Commits](jshint/jshint@2.11.0...2.13.6)

---
updated-dependencies:
- dependency-name: shelljs
  dependency-type: indirect
- dependency-name: jshint
  dependency-type: direct:production
...

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

package.json

@@ -31,7 +31,7 @@
     "gulp-rename": "^1.4.0",
     "gulp-uglify": "^3.0.2",
     "highlight.js": "^10.4.1",
-    "jshint": "^2.11.0",
+    "jshint": "^2.13.6",
     "transfob": "^1.0.0"
   },
   "repository": {