Bump puma from 5.6.2 to 5.6.4

Bumps [puma](https://github.com/puma/puma) from 5.6.2 to 5.6.4.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](https://github.com/puma/puma/compare/v5.6.2...v5.6.4)

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

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

Gemfile

@@ -144,7 +144,7 @@ group :test do
   gem "erb_lint", :require => false
   gem "factory_bot_rails"
   gem "minitest", "~> 5.1"
-  gem "puma", "~> 5.3"
+  gem "puma", "~> 5.6"
   gem "rails-controller-testing"
   gem "rubocop"
   gem "rubocop-minitest"

Gemfile.lock

@@ -362,7 +362,7 @@ GEM
     popper_js (1.16.0)
     progress (3.6.0)
     public_suffix (4.0.6)
-    puma (5.6.2)
+    puma (5.6.4)
       nio4r (~> 2.0)
     quad_tile (1.0.1)
     r2 (0.2.7)
@@ -569,7 +569,7 @@ DEPENDENCIES
   omniauth-windowslive
   openstreetmap-deadlock_retry (>= 1.3.1)
   pg
-  puma (~> 5.3)
+  puma (~> 5.6)
   quad_tile (~> 1.0.1)
   r2 (~> 0.2.7)
   rack-cors