Bump debug from 1.2.0 to 1.2.1

Bumps [debug](https://github.com/ruby/debug) from 1.2.0 to 1.2.1.
- [Release notes](https://github.com/ruby/debug/releases)
- [Commits](https://github.com/ruby/debug/compare/v1.2.0...v1.2.1)

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

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

Gemfile.lock

@@ -70,8 +70,8 @@ GEM
       thor (~> 1.0)
     concurrent-ruby (1.1.9)
     crass (1.0.6)
-    debug (1.2.0)
-      irb
+    debug (1.2.1)
+      irb (>= 1.3.6)
       reline (>= 0.2.7)
     diff-lcs (1.4.4)
     erubi (1.10.0)