feat: relax rack-test dependency to allow version 2 (#270)

rack-test has a number of fixes and improvements:
https://github.com/rack/rack-test/blob/main/History.md

Author: stanhu

example/animal-service/Gemfile.lock

@@ -4,7 +4,7 @@ PATH
     pact (1.62.0)
       pact-mock_service (~> 3.0, >= 3.3.1)
       pact-support (~> 1.16, >= 1.16.9)
-      rack-test (>= 0.6.3, < 2.0.0)
+      rack-test (>= 0.6.3, < 3.0.0)
       rspec (~> 3.0)
       term-ansicolor (~> 1.0)
       thor (>= 0.20, < 2.0)
@@ -46,8 +46,8 @@ GEM
     rack (2.2.4)
     rack-protection (2.2.2)
       rack
-    rack-test (1.1.0)
-      rack (>= 1.0, < 3)
+    rack-test (2.0.2)
+      rack (>= 1.3)
     rainbow (3.1.1)
     rake (13.0.6)
     rspec (3.11.0)

example/zoo-app/Gemfile.lock

@@ -4,7 +4,7 @@ PATH
     pact (1.62.0)
       pact-mock_service (~> 3.0, >= 3.3.1)
       pact-support (~> 1.16, >= 1.16.9)
-      rack-test (>= 0.6.3, < 2.0.0)
+      rack-test (>= 0.6.3, < 3.0.0)
       rspec (~> 3.0)
       term-ansicolor (~> 1.0)
       thor (>= 0.20, < 2.0)
@@ -57,8 +57,8 @@ GEM
       coderay (~> 1.1)
       method_source (~> 1.0)
     rack (2.2.4)
-    rack-test (1.1.0)
-      rack (>= 1.0, < 3)
+    rack-test (2.0.2)
+      rack (>= 1.3)
     rainbow (3.1.1)
     rake (13.0.6)
     rspec (3.11.0)

pact.gemspec

@@ -27,7 +27,7 @@ Gem::Specification.new do |gem|
   }
 
   gem.add_runtime_dependency 'rspec', '~> 3.0'
-  gem.add_runtime_dependency 'rack-test', '>= 0.6.3', '< 2.0.0'
+  gem.add_runtime_dependency 'rack-test', '>= 0.6.3', '< 3.0.0'
   gem.add_runtime_dependency 'thor', '>= 0.20', '< 2.0'
   gem.add_runtime_dependency 'webrick', '~> 1.3'
   gem.add_runtime_dependency 'term-ansicolor', '~> 1.0'