Bump dogstatsd-ruby from 5.6.3 to 5.6.4

Bumps [dogstatsd-ruby](https://github.com/DataDog/dogstatsd-ruby) from 5.6.3 to 5.6.4.
- [Release notes](https://github.com/DataDog/dogstatsd-ruby/releases)
- [Changelog](https://github.com/DataDog/dogstatsd-ruby/blob/master/CHANGELOG.md)
- [Commits](DataDog/dogstatsd-ruby@v5.6.3...v5.6.4)

---
updated-dependencies:
- dependency-name: dogstatsd-ruby
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Gemfile.lock

@@ -136,7 +136,7 @@ GEM
       reline (>= 0.3.8)
     declarative (0.0.20)
     diff-lcs (1.5.1)
-    dogstatsd-ruby (5.6.3)
+    dogstatsd-ruby (5.6.4)
     dotenv (3.1.6)
     dotenv-rails (3.1.6)
       dotenv (= 3.1.6)