Fix Rails 7.1 compatibility by ensuring active_support is required before railtie

Not sure if this is us, strictly speaking but we seem to need to require active_support before the railties or the issue at rails/rails#49495 (comment) occurs

Author: chadlwilson

src/main/ruby/jruby/rack/rails/railtie.rb

@@ -6,6 +6,7 @@
 # See the file LICENSE.txt for details.
 #++
 
+require 'active_support'
 require 'rails/railtie'
 require 'pathname'
 

src/spec/ruby/rails3x/stub/active_support.rb

@@ -0,0 +1,9 @@
+#--
+# Copyright (c) 2010-2012 Engine Yard, Inc.
+# Copyright (c) 2007-2009 Sun Microsystems, Inc.
+# This source code is available under the MIT license.
+# See the file LICENSE.txt for details.
+#++
+
+module ActiveSupport
+end