Bump mocha from 1.1.0 to 1.8.0

Bumps [mocha](https://github.com/freerange/mocha) from 1.1.0 to 1.8.0.
- [Release notes](https://github.com/freerange/mocha/releases)
- [Changelog](https://github.com/freerange/mocha/blob/master/RELEASE.md)
- [Commits](freerange/mocha@v1.1.0...v1.8.0)

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

Gemfile.lock

@@ -63,7 +63,7 @@ GEM
     mini_mime (1.0.1)
     mini_portile2 (2.4.0)
     minitest (5.11.3)
-    mocha (1.1.0)
+    mocha (1.8.0)
       metaclass (~> 0.0.1)
     nokogiri (1.10.1)
       mini_portile2 (~> 2.4.0)