Build(deps): Bump msgpack from 1.5.5 to 1.5.6 (#18061)

Bumps [msgpack](https://github.com/msgpack/msgpack-ruby) from 1.5.5 to 1.5.6.
- [Release notes](https://github.com/msgpack/msgpack-ruby/releases)
- [Changelog](https://github.com/msgpack/msgpack-ruby/blob/master/ChangeLog)
- [Commits](https://github.com/msgpack/msgpack-ruby/compare/v1.5.5...v1.5.6)

---
updated-dependencies:
- dependency-name: msgpack
  dependency-type: indirect
  update-type: version-update:semver-patch
...

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile.lock

@@ -251,7 +251,7 @@ GEM
       ffi (~> 1.9)
     minitest (5.16.3)
     mocha (1.14.0)
-    msgpack (1.5.5)
+    msgpack (1.5.6)
     multi_json (1.15.0)
     multi_xml (0.6.0)
     multipart-post (2.2.3)