Update to tokio 1.37 and various changes

[juicyenc]

This pull request contains commits that:

• Update tokio version to 1.37
• Rewrite tests
• Add github workflow
• Fix rust toolchain to nightly

Tests are rewritten. Now threads are using oneshot channels to synchronize, rather than rely on sleeping time. This makes the test result stable.

Tests uses assert_matches that is experimental in nightly. No other code uses nightly features.