[build] force same AR version default on MRI

Author: kares

Gemfile

@@ -44,7 +44,13 @@ elsif ENV['AR_VERSION'] # Use specific version of AR and not .gemspec version
     end
   end
 else
-  gemspec name: 'activerecord-jdbc-adapter' # Use versiom from .gemspec
+  if defined? JRUBY_VERSION
+    gemspec name: 'activerecord-jdbc-adapter' # Use versiom from .gemspec
+  else # read add_dependency 'activerecord', '~> 7.0' and use the same requirement on MRI
+    ar_req = File.read('activerecord-jdbc-adapter.gemspec').match(/add_dependency.*?activerecord.*['"](.*?)['"]/)[1]
+    raise "add_dependency 'activerecord', ... line not detected in gemspec" unless ar_req
+    gem 'activerecord', ar_req
+  end
 end
 
 gem 'rake', require: nil