Remove NuGet from list of support repository types

[lafrenierejm]

My comment on #3 has details about why NuGet proxying currently does not work:

I can also confirm that this project does not work for NuGet. As I understand it this is because unlike e.g. npm or pip, NuGet uses a handshake protocol for authentication rather than just plain HTTP auth. To be able to proxy NuGet packages from an upstream repository that requires authentication, one would need the proxy server to implement some (if not all) of NuGet's client-side authentication flow.

Here are some relevant resources describing how NuGet auth works:

• https://learn.microsoft.com/en-us/nuget/consume-packages/consuming-packages-authenticated-feeds
• https://learn.microsoft.com/en-us/nuget/reference/extensibility/nuget-cross-platform-plugins#plugin-installation-and-discovery
• https://docs.aws.amazon.com/codeartifact/latest/ug/nuget-cli.html