Avoid tokio-stream dependency when using a runtime other than tokio

[maxbrunsfeld]

This is a follow-up to #310

When building the main livekit crate the async or dispatcher features (as opposed to the default tokio feature), we already have a dependency on the futures crate, which provides the Stream trait, so we don't need a dependency on tokio-stream.

As a drive-by, I fixed a test that was failing in CI due to a missing tokio runtime, by applying the tokio::test macro to that test (which sets up a tokio runtime automatically).

[maxbrunsfeld]

It looks like the yuv-sys crate is failing to build on the android targets:

[yuv-sys 0.3.6] exit status: 0
[yuv-sys 0.3.6] cargo:rustc-link-lib=static=yuv
[yuv-sys 0.3.6] cargo:rustc-link-search=native=/home/runner/work/rust-sdks/rust-sdks/target/aarch64-linux-android/release/build/yuv-sys-fbedbf06764db0b3/out
[yuv-sys 0.3.6] /usr/include/stdint.h:26:10: fatal error: 'bits/libc-header-start.h' file not found
[yuv-sys 0.3.6] thread 'main' panicked at /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/yuv-sys-0.3.6/build.rs:141:37:
[yuv-sys 0.3.6] called `Result::unwrap()` on an `Err` value: ClangDiagnostic("/usr/include/stdint.h:26:10: fatal error: 'bits/libc-header-start.h' file not found\n")
[yuv-sys 0.3.6] note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
error: failed to run custom build command for `yuv-sys v0.3.6`

[theomonnom]

It looks like the yuv-sys crate is failing to build on the android targets:

Seems unrelated to this PR

[theomonnom]

lgtm, thanks!