Respect UV_INDEX_ rather than UV_HTTP_BASIC_

[odie5533]

The docs reference UV_INDEX_, but the code actually uses UV_HTTP_BASIC_ as the prefix for environment variable credentials.

See PR #7741

Code is at https://github.com/astral-sh/uv/blob/main/crates/uv-static/src/env_vars.rs#L163

    /// Generates the environment variable key for the HTTP Basic authentication username.
    pub fn http_basic_username(name: &str) -> String {
        format!("UV_HTTP_BASIC_{name}_USERNAME")
    }

    /// Generates the environment variable key for the HTTP Basic authentication password.
    pub fn http_basic_password(name: &str) -> String {
        format!("UV_HTTP_BASIC_{name}_PASSWORD")
    }

[zanieb]

@charliermarsh I can't remember which one of these we thought was better. Wasn't it the UV_INDEX_ prefix?

[zanieb]

(That's also what's mentioned in the PR summary, so I presume the code is wrong here)

[charliermarsh]

Oh I think I meant to do UV_HTTP_BASIC but honestly I can't remember

[zanieb]

I thought we were intentionally deviating from what Poetry does?

[charliermarsh]

I don't remember honestly. We can't easily change it now that it's out there though -- it would be breaking.

[odie5533]

It's possible I might be the only one that's used it successfully though 🤣
and I don't mind you breaking it on me

[charliermarsh]

I guess we could call it a bug since the documentation differs. That seems fine, actually. Ok, lets use UV_INDEX_INTERNAL_USERNAME and UV_INDEX_INTERNAL_PASSWORD.

[zanieb]

Thank you!