Bump puma from 3.12.1 to 3.12.6

Bumps [puma](https://github.com/puma/puma) from 3.12.1 to 3.12.6.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](https://github.com/puma/puma/commits)

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

Author: dependabot[bot]

Gemfile.lock

@@ -164,7 +164,7 @@ GEM
     pry-rails (0.3.9)
       pry (>= 0.10.4)
     public_suffix (3.1.1)
-    puma (3.12.4)
+    puma (3.12.6)
     rack (2.0.7)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)