Windows can't run integration tests with tls-rustls or tls-default features

[clintfred]

This was discovered on CI.

To reproduce (on windows):

• cargo test --features tls-rustls --no-default-features
• cargo test (default features)

Both of these should work as rustls is pure rust and the default should use the windows TLS implementation.

Workaround for now is to use tls-vendored-openssl
cargo test --features tls-vendored-openssl --no-default-features

Once we have validated that all TLS combinations work, we should update CI to use the windows native (default) TLS as that is what what most Windows applications would probably want.