bump rack in test Gemfile

Author: GrantBirki

spec/acceptance/github-server/Gemfile

@@ -2,7 +2,7 @@
 
 source "https://rubygems.org"
 
-gem "rack", "= 2.2.8"
+gem "rack", "= 2.2.8.1"
 gem "rack-test", "~> 2.1"
 gem "sinatra", "= 3.2.0"
 gem "webrick", "~> 1.8"