Bump gulp-mocha from 7.0.2 to 8.0.0 (#254)

Bumps [gulp-mocha](https://github.com/sindresorhus/gulp-mocha) from 7.0.2 to 8.0.0.
- [Release notes](https://github.com/sindresorhus/gulp-mocha/releases)
- [Commits](sindresorhus/gulp-mocha@v7.0.2...v8.0.0)

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Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]

package.json

@@ -54,7 +54,7 @@
     "gulp-exec": "^5.0.0",
     "gulp-header": "^2.0.5",
     "gulp-less": "^4.0.1",
-    "gulp-mocha": "^7.0.0",
+    "gulp-mocha": "^8.0.0",
     "gulp-sass": "^4.1.0",
     "gulp-stylelint": "^13.0.0",
     "jsdom": "^16.0.1",