Bump minitest from 5.3.5 to 5.12.0

Bumps [minitest](https://github.com/minitest/minitest) from 5.3.5 to 5.12.0.
- [Changelog](https://github.com/minitest/minitest/blob/master/History.rdoc)
- [Commits](minitest/minitest@v5.3.5...v5.12.0)

---
updated-dependencies:
- dependency-name: minitest
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Gemfile

@@ -1,7 +1,7 @@
 source "https://rubygems.org"
 
 gem "rake", "~> 10.3.2"
-gem "minitest", "~> 5.3.5"
+gem "minitest", "~> 5.12.0"
 gem "i18n", "~> 1.8.5"
 
 gemspec

Gemfile.lock

@@ -9,7 +9,7 @@ GEM
     concurrent-ruby (1.1.7)
     i18n (1.8.5)
       concurrent-ruby (~> 1.0)
-    minitest (5.3.5)
+    minitest (5.12.0)
     rake (10.3.2)
 
 PLATFORMS
@@ -18,7 +18,7 @@ PLATFORMS
 DEPENDENCIES
   gemoji!
   i18n (~> 1.8.5)
-  minitest (~> 5.3.5)
+  minitest (~> 5.12.0)
   rake (~> 10.3.2)
 
 BUNDLED WITH