Bump Puma

Gemfile.lock

@@ -255,7 +255,7 @@ GEM
       byebug (~> 11.0)
       pry (~> 0.13.0)
     public_suffix (4.0.6)
-    puma (5.5.2)
+    puma (5.6.0)
       nio4r (~> 2.0)
     racc (1.6.0)
     rack (2.2.3)
@@ -316,7 +316,7 @@ GEM
     rspec-mocks (3.10.2)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.10.0)
-    rspec-rails (5.0.2)
+    rspec-rails (5.1.0)
       actionpack (>= 5.2)
       activesupport (>= 5.2)
       railties (>= 5.2)