* Add the `rust-version` key to each Cargo manifest
* Normalize dependencies and features in each Cargo manifest
* Enable all features in CI when checking examples
* Update the top-level README
* CS impl
* use CS Mutex in C3 examples
* use CS Mutex in S2 examples
* Update esp32 example
* run fmt
* Update S3 examples
* Remove uses of unsafe where no longer required
* use esp_backtrace in examples
* fix import & fmt once more
* Bump MSRV to 1.60.0
Co-authored-by: Jesse Braham <jesse@beta7.io>
