Post request parameters should be passed in data param

[oli-pr]

AuthAtCloudFrontEdge/us-east-1/Lambda@Edge/EdgeLambda/SignIn/signin.py

Line 76 in 4d633e8

resp = requests.post(USER_POOL_ENDPOINT, params=payload, headers=headers)

I think this needs to be resp = requests.post(USER_POOL_ENDPOINT, data=payload, headers=headers) from testing