Bump rubocop from 1.31.0 to 1.31.1

Bumps [rubocop](https://github.com/rubocop/rubocop) from 1.31.0 to 1.31.1.
- [Release notes](https://github.com/rubocop/rubocop/releases)
- [Changelog](https://github.com/rubocop/rubocop/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop@v1.31.0...v1.31.1)

---
updated-dependencies:
- dependency-name: rubocop
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

Gemfile.lock

@@ -9,6 +9,7 @@ GEM
   specs:
     ast (2.4.2)
     docile (1.4.0)
+    json (2.6.2)
     minitest (5.16.1)
     parallel (1.22.1)
     parser (3.1.2.0)
@@ -18,7 +19,8 @@ GEM
     rake (13.0.6)
     regexp_parser (2.5.0)
     rexml (3.2.5)
-    rubocop (1.31.0)
+    rubocop (1.31.1)
+      json (~> 2.3)
       parallel (~> 1.10)
       parser (>= 3.1.0.0)
       rainbow (>= 2.2.2, < 4.0)