update app.py

'key' needs to be added in front of the Access Key. I also added 'Content-Type': 'application/json'
Didn't work for me until I changed those 2 things

flask_app/app.py

@@ -121,7 +121,8 @@ def get_new_data():
         endpoint = "https://{app}.data.thethingsnetwork.org/api/v2/query/{dev}?last={time}".format(
             app=application, dev=each_device, time="{}s".format(past_seconds))
         logger.info(endpoint)
-        headers = {"Authorization": app_key}
+        key = 'key {}'.format(app_key)
+        headers = {'Authorization': key, 'Content-Type': 'application/json'}
         response = requests.get(endpoint, headers=headers)
         try:
             for each_resp in response.json():