Bump puma from 3.12.1 to 4.0.0

Bumps [puma](https://github.com/puma/puma) from 3.12.1 to 4.0.0.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](puma/puma@v3.12.1...v4.0.0)

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

Gemfile.lock

@@ -240,7 +240,8 @@ GEM
     pghero (2.2.1)
       activerecord
     public_suffix (3.1.0)
-    puma (3.12.1)
+    puma (4.0.0)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-accept-default (0.0.2)
       rack