DeserializejsondateofdateinFlaskapp

I have a Flask application that requires the user's date of birth for registration. A request looks something like this.

{
    "username":"tayy",
    "email":"tayy@dvm.com",
    "password":"897ghTR$%dsa",
    "first_name":"Tay",
    "last_name":"Young",
    "dob":"1995-01-01"
}

I am trying to deserialize the date of birth (dob). I have spent about 4 hours searching the internet for something, but so far I have come up short. The biggest issue I am running into is my data sits in a dictionary and most of the solutions only work with variables. Here is the relevent portion of the code:

@user_api.route('/', methods=['POST'])
def create():
  """
  Create User Function
  """
  req_data = request.get_json()
  print("- - - - - - - - - - - - - - - - - - - - -")
  print ("This is the data from the request:")
  print (request.get_json())
  print("- - - - - - - - - - - - - - - - - - - - -")
  data, error = user_schema.load(req_data)

  if error:
    return custom_response(error, 400)

  # check if user already exist in the db
  user_in_db = UserModel.get_user_by_email(data.get('email'))
  if user_in_db:
    message = {'error': 'User already exist, please supply another email address'}
    return custom_response(message, 400)

  user = UserModel(data)
  user.save()
  ser_data = user_schema.dump(user).data
  token = Auth.generate_token(ser_data.get('id'))
  return custom_response({'jwt_token': token}, 201)

How can I deserealize this date so I can insert it into my Postgres database?