feat: add application/json support for client

twilio/http/http_client.py

@@ -79,12 +79,16 @@ def request(
             "method": method.upper(),
             "url": url,
             "params": params,
-            "data": data,
             "headers": headers,
             "auth": auth,
             "hooks": self.request_hooks,
         }
 
+        if headers is not None and 'Content-Type' in headers.keys() and headers['Content-Type'] == 'application/json':
+            kwargs['json'] = data
+        else:
+            kwargs['data'] = data
+
         self.log_request(kwargs)
 
         self._test_only_last_response = None