Bump concurrent-ruby from 1.2.3 to 1.3.1

Bumps [concurrent-ruby](https://github.com/ruby-concurrency/concurrent-ruby) from 1.2.3 to 1.3.1.
- [Release notes](https://github.com/ruby-concurrency/concurrent-ruby/releases)
- [Changelog](https://github.com/ruby-concurrency/concurrent-ruby/blob/master/CHANGELOG.md)
- [Commits](ruby-concurrency/concurrent-ruby@v1.2.3...v1.3.1)

---
updated-dependencies:
- dependency-name: concurrent-ruby
  dependency-type: indirect
  update-type: version-update:semver-minor
...

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

Gemfile.lock

@@ -155,7 +155,7 @@ GEM
       descendants_tracker (~> 0.0.1)
     colored (1.2)
     commonmarker (1.1.3-x86_64-linux)
-    concurrent-ruby (1.2.3)
+    concurrent-ruby (1.3.1)
     connection_pool (2.4.1)
     crass (1.0.6)
     cuprite (0.15)