Bump debug and gulp-livereload

Bumps [debug](https://github.com/debug-js/debug) to 2.6.9 and updates ancestor dependency [gulp-livereload](https://github.com/vohof/gulp-livereload). These dependencies need to be updated together.


Updates `debug` from 2.2.0 to 2.6.9
- [Release notes](https://github.com/debug-js/debug/releases)
- [Changelog](https://github.com/debug-js/debug/blob/2.6.9/CHANGELOG.md)
- [Commits](https://github.com/debug-js/debug/compare/2.2.0...2.6.9)

Updates `gulp-livereload` from 3.8.1 to 4.0.2
- [Release notes](https://github.com/vohof/gulp-livereload/releases)
- [Changelog](https://github.com/gulp-community/gulp-livereload/blob/master/CHANGELOG.md)
- [Commits](https://github.com/vohof/gulp-livereload/compare/v3.8.1...v4.0.2)

---
updated-dependencies:
- dependency-name: debug
  dependency-type: indirect
- dependency-name: gulp-livereload
  dependency-type: direct:development
...

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

package.json

@@ -33,7 +33,7 @@
     "gulp-inject-string": "^1.1.0",
     "gulp-inline-css": "^3.1.0",
     "gulp-less": "3.1.0",
-    "gulp-livereload": "3.8.1",
+    "gulp-livereload": "4.0.2",
     "gulp-load-plugins": "1.2.4",
     "gulp-notify": "2.2.0",
     "gulp-plumber": "1.1.0",