Bump rubocop from 1.19.1 to 1.20.0

Bumps [rubocop](https://github.com/rubocop/rubocop) from 1.19.1 to 1.20.0.
- [Release notes](https://github.com/rubocop/rubocop/releases)
- [Changelog](https://github.com/rubocop/rubocop/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rubocop/rubocop/compare/v1.19.1...v1.20.0)

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

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

Gemfile.lock

@@ -192,7 +192,7 @@ GEM
     regexp_parser (2.1.1)
     rexml (3.2.5)
     rouge (3.26.0)
-    rubocop (1.19.1)
+    rubocop (1.20.0)
       parallel (~> 1.10)
       parser (>= 3.0.0.0)
       rainbow (>= 2.2.2, < 4.0)
@@ -201,7 +201,7 @@ GEM
       rubocop-ast (>= 1.9.1, < 2.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 1.4.0, < 3.0)
-    rubocop-ast (1.10.0)
+    rubocop-ast (1.11.0)
       parser (>= 3.0.1.1)
     ruby-enum (0.8.0)
       i18n