Use released version of Rack

Gemfile

@@ -9,9 +9,7 @@ gem "sinatra"
 gem "rackup", "~> 2.1"
 
 gem "sinatra-contrib", "~> 4.0"
-# Use pre-released version for "Partitioned" cookie support:
-# https://github.com/rack/rack/commit/958ed518cda851546c4d26ff9fd4db6255bd4021
-gem "rack", github: "rack/rack", ref: "8c73aefcc7085c71bdfe6c1ec867f126ede34124"
+gem "rack", "~> 3.1"
 # Use pre-released version for "assume_ssl" option to make "secure" option work in development:
 # https://github.com/rack/rack-session/commit/219d8da15b0d1a02c650f956df29db42408a6adb
 gem "rack-session", github: "rack/rack-session", ref: "219d8da15b0d1a02c650f956df29db42408a6adb"

Gemfile.lock

@@ -7,13 +7,6 @@ GIT
       base64 (>= 0.1.0)
       rack (>= 3.0.0)
 
-GIT
-  remote: https://github.com/rack/rack.git
-  revision: 8c73aefcc7085c71bdfe6c1ec867f126ede34124
-  ref: 8c73aefcc7085c71bdfe6c1ec867f126ede34124
-  specs:
-    rack (3.0.0)
-
 GEM
   remote: https://rubygems.org/
   specs:
@@ -43,6 +36,7 @@ GEM
     psych (5.1.2)
       stringio
     public_suffix (5.0.4)
+    rack (3.1.8)
     rack-protection (4.0.0)
       base64 (>= 0.1.0)
       rack (>= 3.0.0, < 4)
@@ -81,7 +75,7 @@ PLATFORMS
 DEPENDENCIES
   debug (~> 1.9)
   octokit (~> 8.1)
-  rack!
+  rack (~> 3.1)
   rack-session!
   rackup (~> 2.1)
   sinatra