Credentials being cached between requests to separate remotes with the same URL

The current implementation of ManagedHttpSmartSubtransportStream uses a static CredentialCache. The credentials in this cache are only differentiated by URL and authentication scheme, if you have two separate repositories configured with the same URL, it's possible to authenticate to a repository without providing valid credentials.

Reproduction steps

using System;
using System.Net;
using LibGit2Sharp;

namespace Example
{
    class Program
    {
        static void Main(string[] args)
        {
            var uri = "<repository URL>";

            var repo1 = Repository.Clone(uri, "directory1", new CloneOptions
            {
                BranchName = "main",
                CredentialsProvider = CredentialsHandlerThatReturnsValidCredentials
            }); // This will succeed

            var repo2 = Repository.Clone(uri, "directory2", new CloneOptions
            {
                BranchName = "main",
                CredentialsProvider = CredentialHandlerThatReturnsInvalidCredentials
            }); // Invalid credential provider is never called, cached credentials from the first request are used
        }

        public static Credentials CredentialsHandlerThatReturnsValidCredentials(string url, string usernameFromUrl,
            SupportedCredentialTypes types)
        {
            return new UsernamePasswordCredentials
            {
                Username = "<valid username>",
                Password = "<valid password>"
            };
        }

        public static Credentials CredentialHandlerThatReturnsInvalidCredentials(string url, string usernameFromUrl,
            SupportedCredentialTypes types)
        {
            return new UsernamePasswordCredentials
            {
                Username = "invalid username",
                Password = "invalid password"
            };
        }
    }
}

Expected behavior

Second clone should not authenticate, invalid credentials supplied.

Actual behavior

Authenticates with repository successfully, as there has already been a successful authentication to that repository URL.

Version of LibGit2Sharp (release number or SHA1)

0.27.0-preview-0102

Operating system(s) tested; .NET runtime tested

macOS, .NET 5

Start in LibGit2Sharp/Core/ManagedHttpSmartSubtransport.cs, especially the static CredentialCache used by ManagedHttpSmartSubtransportStream. Reproduce the two clones with the same URL and separate credential providers, then verify that the second provider is called and invalid credentials do not authenticate successfully.