Bump puma from 4.3.5 to 4.3.8

Bumps [puma](https://github.com/puma/puma) from 4.3.5 to 4.3.8.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](puma/puma@v4.3.5...v4.3.8)

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

Gemfile.lock

@@ -204,7 +204,7 @@ GEM
     mini_portile2 (2.5.1)
     minitest (5.14.3)
     multi_json (1.14.1)
-    nio4r (2.5.4)
+    nio4r (2.5.7)
     nokogiri (1.11.4)
       mini_portile2 (~> 2.5.0)
       racc (~> 1.4)
@@ -227,7 +227,7 @@ GEM
       prawn (>= 0.11.1)
       railties (>= 3.0.0)
     public_suffix (4.0.1)
-    puma (4.3.5)
+    puma (4.3.8)
       nio4r (~> 2.0)
     racc (1.5.2)
     rack (1.6.12)