Bump mocha from 2.5.0 to 2.6.1

Bumps [mocha](https://github.com/freerange/mocha) from 2.5.0 to 2.6.1.
- [Changelog](https://github.com/freerange/mocha/blob/main/RELEASE.md)
- [Commits](freerange/mocha@v2.5.0...v2.6.1)

---
updated-dependencies:
- dependency-name: mocha
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile.lock

@@ -373,7 +373,7 @@ GEM
       ruby-progressbar
     mlanett-redis-lock (0.2.7)
       redis
-    mocha (2.5.0)
+    mocha (2.6.1)
       ruby2_keywords (>= 0.0.5)
     momentjs-rails (2.29.4.1)
       railties (>= 3.1)