Bump puma from 5.6.7 to 5.6.8 in /examples/stacks/rails/blog (#1706)

Author: dependabot[bot]

examples/stacks/rails/blog/Gemfile.lock

@@ -124,15 +124,15 @@ GEM
       timeout
     net-smtp (0.3.3)
       net-protocol
-    nio4r (2.5.9)
+    nio4r (2.7.0)
     nokogiri (1.14.3-arm64-darwin)
       racc (~> 1.4)
     nokogiri (1.14.3-x86_64-darwin)
       racc (~> 1.4)
     nokogiri (1.14.3-x86_64-linux)
       racc (~> 1.4)
     public_suffix (5.0.1)
-    puma (5.6.7)
+    puma (5.6.8)
       nio4r (~> 2.0)
     racc (1.6.2)
     rack (2.2.6.4)