Bump puma from 2.9.1 to 5.6.2

Bumps [puma](https://github.com/puma/puma) from 2.9.1 to 5.6.2.
- [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/v2.9.1...v5.6.2)

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

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

Gemfile.lock

@@ -208,6 +208,7 @@ GEM
     net-ssh-gateway (1.2.0)
       net-ssh (>= 2.6.5)
     newrelic_rpm (3.9.5.251)
+    nio4r (2.5.8)
     nokogiri (1.6.3.1)
       mini_portile (= 0.6.0)
     non-stupid-digest-assets (1.0.4)
@@ -216,11 +217,11 @@ GEM
     polyamorous (1.1.0)
       activerecord (>= 3.0)
     polyglot (0.3.5)
-    puma (2.9.1)
+    puma (5.6.2)
-      rack (>= 1.1, < 2.0)
+      nio4r (~> 2.0)
     quiet_assets (1.0.3)
       railties (>= 3.1, < 5.0)
-    rack (1.5.2)
+    rack (1.5.5)
     rack-protection (1.5.3)
       rack
     rack-test (0.6.2)