Bump puma from 3.12.0 to 3.12.6

Bumps [puma](https://github.com/puma/puma) from 3.12.0 to 3.12.6.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](puma/puma@v3.12.0...v3.12.6)

---
updated-dependencies:
- dependency-name: puma
  dependency-type: indirect
...

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

Gemfile.lock

@@ -11,12 +11,12 @@ PATH
 GEM
   remote: https://rubygems.org/
   specs:
-    addressable (2.5.2)
-      public_suffix (>= 2.0.2, < 4.0)
+    addressable (2.8.4)
+      public_suffix (>= 2.0.2, < 6.0)
     builder (3.2.4)
     coderay (1.1.2)
     docile (1.1.5)
-    ffi (1.15.5-java)
+    ffi (1.12.2-java)
     json (2.1.0)
     json (2.1.0-java)
     launchy (2.4.3)
@@ -31,9 +31,9 @@ GEM
     minitest-junit (1.1.0)
       builder (~> 3.2)
       minitest (~> 5.11)
-    public_suffix (3.0.3)
-    puma (3.12.0)
-    puma (3.12.0-java)
+    public_suffix (3.1.1)
+    puma (3.12.6)
+    puma (3.12.6-java)
     rack (2.0.5)
     rake (12.3.0)
     rdoc (6.0.1)