fix: use to_json instead of JSON.dump because it generates different JSON when used in conjuction with other libraries (eg. Oj)

Author: bethesque

lib/pact/hal/link.rb

@@ -41,11 +41,11 @@ def get(payload = {}, headers = {})
       end
 
       def put(payload = nil, headers = {})
-        wrap_response(href, @http_client.put(href, payload ? JSON.dump(payload) : nil, headers))
+        wrap_response(href, @http_client.put(href, payload ? payload.to_json : nil, headers))
       end
 
       def post(payload = nil, headers = {})
-        wrap_response(href, @http_client.post(href, payload ? JSON.dump(payload) : nil, headers))
+        wrap_response(href, @http_client.post(href, payload ? payload.to_json : nil, headers))
       end
 
       def expand(params)