Using custom pypi-server doesn't work for some use cases

Using custom pypi-server doesn't work for my use case, pipreqs assumes that repo folder is "json" but in my case it "simple"

For example, my index-url=https://myorg.com/api/pypi/pypi/simple/
when I run:
pipreqs --force --pypi-server https://myorg.com/api/pypi/pypi/simple/ or pipreqs --force --pypi-server https://myorg.com/api/pypi/pypi/

I get:
WARNING: Package ... does not exist or network problems and not all the requirements are generated
because pipreqs is appending "/json" to the end of pypi-server which doesn't exist in my environment.

Inspect the --pypi-server handling and the URL construction used when pipreqs queries package metadata. Reproduce the issue with the provided simple endpoint, then verify that a compatible custom index is queried without assuming a /json path and that requirements are generated successfully.

Written by the indexing model from the issue text.