Bump puma from 6.4.2 to 6.4.3

Bumps [puma](https://github.com/puma/puma) from 6.4.2 to 6.4.3.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](puma/puma@v6.4.2...v6.4.3)

---
updated-dependencies:
- dependency-name: puma
  dependency-type: direct:production
...

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

Gemfile.lock

@@ -24,14 +24,14 @@ GEM
     mustermann (2.0.2)
       ruby2_keywords (~> 0.0.1)
     mutex_m (0.2.0)
-    nio4r (2.7.0)
+    nio4r (2.7.3)
     pry (0.14.2)
       coderay (~> 1.1)
       method_source (~> 1.0)
     pry-remote (0.1.8)
       pry (~> 0.9)
       slop (~> 3.0)
-    puma (6.4.2)
+    puma (6.4.3)
       nio4r (~> 2.0)
     rack (2.2.8.1)
     rack-protection (2.2.4)