get_the_latest_contract_1.py

from datetime import datetime

contracts = [
    {
      "id": 157289,
      "id_cliente": 118801,
      "nome": "FULANO DA SILVA",
      "data_gerado": "2019-04-30"
    },
    {
      "id": 142032,
      "id_cliente": 118801,
      "nome": "FULANO DA SILVA",
      "data_gerado": "2020-09-04"
    },
    {
      "id": 269493,
      "id_cliente": 118805,
      "nome": "RANGEL LUIZ DOS SANTOS",
      "prazo": 12,
      "data_gerado": "2021-10-22"
    },
    {
      "id": 146051,
      "id_cliente": 118805,
      "nome": "RANGEL LUIZ DOS SANTOS",
      "prazo": 12,
      "data_gerado": "2016-03-05"
    },
    {
      "id": 145356,
      "id_cliente": 118805,
      "nome": "RANGEL LUIZ DOS SANTOS",
      "prazo": 12,
      "data_gerado": "2018-03-05"
    }  
]

print(sorted(contracts, key=lambda contrato: datetime.strptime(contrato['data_gerado'], '%Y-%M-%d')).pop())

get_the_latest_contract_2.py

from datetime import datetime
from operator import itemgetter


def convert_to_datetime(string):
    return datetime.strptime(string, '%Y-%M-%d')


def as_datetime(function):
    def wrapper(obj):
        return convert_to_datetime(function(obj))
    return wrapper        


contracts = [
    {
      "id": 157289,
      "id_cliente": 118801,
      "nome": "FULANO DA SILVA",
      "data_gerado": "2019-04-30"
    },
    {
      "id": 142032,
      "id_cliente": 118801,
      "nome": "FULANO DA SILVA",
      "data_gerado": "2020-09-04"
    },
    {
      "id": 269493,
      "id_cliente": 118805,
      "nome": "RANGEL LUIZ DOS SANTOS",
      "prazo": 12,
      "data_gerado": "2021-10-22"
    },
    {
      "id": 146051,
      "id_cliente": 118805,
      "nome": "RANGEL LUIZ DOS SANTOS",
      "prazo": 12,
      "data_gerado": "2016-03-05"
    },
    {
      "id": 145356,
      "id_cliente": 118805,
      "nome": "RANGEL LUIZ DOS SANTOS",
      "prazo": 12,
      "data_gerado": "2018-03-05"
    }  
]

get_contract_date = as_datetime(itemgetter('data_gerado'))
print(sorted(contracts, key=get_contract_date).pop())