[Security] Bump puma from 4.3.1 to 4.3.8

Bumps [puma](https://github.com/puma/puma) from 4.3.1 to 4.3.8. **This update includes security fixes.**
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](puma/puma@v4.3.1...v4.3.8)

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

Gemfile.lock

@@ -165,7 +165,7 @@ GEM
     multi_xml (0.6.0)
     multipart-post (2.1.1)
     nenv (0.3.0)
-    nio4r (2.5.2)
+    nio4r (2.5.7)
     nokogiri (1.10.5)
       mini_portile2 (~> 2.4.0)
     notiffany (0.1.3)
@@ -223,7 +223,7 @@ GEM
       pry (>= 0.9.10, < 0.12.0)
     psych (3.1.0)
     public_suffix (4.0.1)
-    puma (4.3.1)
+    puma (4.3.8)
       nio4r (~> 2.0)
     rack (2.0.8)
     rack-cors (1.0.3)