There are a lot of ways to generate random values. But some of them are not suitable for secret keys. There is a new module named secrets in version 3.6 and later. You can use the code below to generate cryptographically strong random values.
import secrets secrets.token_hex()
This module will generate truly random values not pseudo-random. Pseudo-random generators should be used only for simulation, not important random values or anything security related. You can use secrets for data such as password, security tokens and etc.