Remove usage of actions-rs/clippy-check

[taiki-e]

#286, #384, and #385's CI is failing because of this error. I think this action is broken.

https://github.com/async-rs/async-std/pull/286/checks?check_run_id=276113673:

##[error]Unable to create clippy annotations! Reason: HttpError: Resource not accessible by integration
##[warning]It seems that this Action is executed from the forked repository.
##[warning]GitHub Actions are not allowed to create Check annotations, when executed for a forked repos. See https://github.com/actions-rs/clippy-check/issues/2 for details.
Posting clippy checks here instead.

Related: actions-rs/clippy-check#2 (comment)

[taiki-e]

Nope, CI fails are due to clippy bug...

error: do not call a function with mutable arguments inside of `debug_assert!`
  --> src/io/buf_read/read_line.rs:40:27
   |
40 |             debug_assert!(buf.is_empty());
   |                           ^^^^^^^^^^^^^^
   |
   = note: `#[deny(clippy::debug_assert_with_mut_call)]` on by default
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#debug_assert_with_mut_call

UPDATE: filed rust-lang/rust-clippy#4737

[ghost]

Let's just delete the whole Clippy check? I think Clippy is useful during development but is not really suitable for continuous integration :)

[taiki-e]

Let's just delete the whole Clippy check? I think Clippy is useful during development but is not really suitable for continuous integration :)

I think we should use the beta's clippy. nightly's clippy often adds broken lint, so I think it's not really suitable for CI.

[skade]

Let's try out Beta for a while and see if it improves things.