Use custom pypi repository

Hi,

we have a pypi repository in CodeArtifact where we push some in-house developed python packages.
Now we would like to use that private pypi repository in our lambda so it can download those "private" packages.

I've been reading the [builder code](https://github.com/aws/aws-lambda-builders/blob/develop/aws_lambda_builders/builder.py) but I do not find a way to configure/use a custom pypi repository.

To my understanding I have two options:

- create a custom Docker image where pypi repo is preconfigured and use it to build the lambda
- upload all packages (dependencies) together with the lambda

I'm not an expert and I was wondering if someone could provide some hint on how to get the custom repo in the lambda though the lambdabuilder instead of going into one of the above options I've listed.

thanks