Bump Puma to v5.3.1 (#13731)

This required an explicit `Gemfile` change because `bundle update puma`
did not actually update otherwise:

    Bundler attempted to update puma but its version stayed the same

Gemfile

@@ -67,7 +67,7 @@ gem "parallel", "~> 1.20" # Run any kind of code in parallel processes
 gem "patron", "~> 0.13.3" # HTTP client library based on libcurl, used with GitHub OAuth client
 gem "pg", "~> 1.2" # Pg is the Ruby interface to the PostgreSQL RDBMS
 gem "pg_search", "~> 2.3.5" # PgSearch builds Active Record named scopes that take advantage of PostgreSQL's full text search
-gem "puma", "~> 5.2.2" # Puma is a simple, fast, threaded, and highly concurrent HTTP 1.1 server
+gem "puma", "~> 5.3.1" # Puma is a simple, fast, threaded, and highly concurrent HTTP 1.1 server
 gem "pundit", "~> 2.1" # Object oriented authorization for Rails applications
 gem "pusher", "~> 2.0" # Ruby library for Pusher Channels HTTP API
 gem "rack-attack", "~> 6.5.0" # Used to throttle requests to prevent brute force attacks

Gemfile.lock

@@ -518,7 +518,7 @@ GEM
     pry-rails (0.3.9)
       pry (>= 0.10.4)
     public_suffix (4.0.6)
-    puma (5.2.2)
+    puma (5.3.1)
       nio4r (~> 2.0)
     pundit (2.1.0)
       activesupport (>= 3.0.0)
@@ -929,7 +929,7 @@ DEPENDENCIES
   pry (~> 0.13)
   pry-byebug (~> 3.8)
   pry-rails (~> 0.3)
-  puma (~> 5.2.2)
+  puma (~> 5.3.1)
   pundit (~> 2.1)
   pundit-matchers (~> 1.6)
   pusher (~> 2.0)