FastAPI, MongoDB, Docker Compose - User authentication

How to make a backend-end for a simple user authentication in FastAPI, MongoDB as database, docker compose deployment.
Files link on the github:

[bertrandb]

There is un error with the get/ list users : 

response -> 32 -> _id
Invalid objectid (type=value_error)
response -> 32 -> created_at
str type expected (type=type_error.str)
response -> 32 -> last_login
str type expected (type=type_error.str)

if you have the solution ? i'm trying to solve it....