Bump gulp-mocha from 7.0.2 to 8.0.0

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)

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

package.json

@@ -33,7 +33,7 @@
     "chai-as-promised": "7.1.1",
     "codecov.io": "0.1.6",
     "gulp": "4.0.2",
-    "gulp-mocha": "7.0.2",
+    "gulp-mocha": "8.0.0",
     "istanbul": "0.4.5",
     "mocha": "8.3.0",
     "request-promise": "4.2.6"