Bump gulp-mocha from 6.0.0 to 7.0.2

Bumps [gulp-mocha](https://github.com/sindresorhus/gulp-mocha) from 6.0.0 to 7.0.2.
- [Release notes](https://github.com/sindresorhus/gulp-mocha/releases)
- [Commits](sindresorhus/gulp-mocha@v6.0.0...v7.0.2)

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": "6.0.0",
+    "gulp-mocha": "7.0.2",
     "istanbul": "0.4.5",
     "mocha": "7.1.2",
     "request-promise": "4.2.5"