* ci: use same feature set in `build_dev` and `build_release`
* ci: also enable unstable tokio for `build_dev`
* chore: update tokio to 1.21 (to fix console-subscriber 0.1.8
* fix: "must use"
* feat: async sleep with `TimeProvider`
This is helpful to mock "ticked" loops or to control certain async time
periods.
Will be used to test the refresh policy developed in #5318.
* refactor: use a single `TimeProvider::sleep` impl
Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>