security: Avoid using buggy atty crate

[Techcable]

Switches to newer is-terminal crate instead.
This functionality is also availible on the nightly Rust stdlib as a std::io::IsTerminal trait.

Avoids RUSTSEC-2021-0145 (softprops/atty#50)
Fixes slog-rs/slog#319

Based on the information in the vulnerability database, I don't consider this a particularly serious bug.

In practice however, the pointer won't be unaligned
unless a custom global allocator is used.

[willbuckner]

Looks great, thanks!

[willbuckner]

Downloaded once_cell v1.16.0
error: failed to parse manifest at `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/once_cell-1.16.0/Cargo.toml`

Caused by:
  feature `edition[20](https://github.com/slog-rs/term/actions/runs/3562324356/jobs/5983962221#step:4:21)[21](https://github.com/slog-rs/term/actions/runs/3562324356/jobs/5983962221#step:4:22)` is required

  this Cargo does not support nightly features, but if you
  switch to nightly channel you can add
  `cargo-features = ["edition2021"]` to enable this feature
Error: Process completed with exit code 101.

[sunfishcode]

That appears to be an unrelated issue. once_cell, which term already depends on through thread_local, recently updated to use edition = "2021", which is incompatible with Rust 1.53.

You can work around this issue by downgrading once_cell from 1.16.0 to 1.14.0, such as by this command:

cargo update --package once_cell --precise 1.14.0

[Techcable]

That appears to be an unrelated issue. once_cell, which term already depends on through thread_local, recently updated to use edition = "2021", which is incompatible with Rust 1.53.

You can work around this issue by downgrading once_cell from 1.16.0 to 1.14.0, such as by this command:

cargo update --package once_cell --precise 1.14.0

Yes. Unfortunately cargo's dependency resolver doesn't respect Rust MSRV requirements :/

[adamchalmers]

Hello! Just wondering if @Techcable I can help moving this PR forward. I'd like this PR merged because it's starting to give me GitHub dependabot warnings. Obviously I can just dismiss them (the atty issue cannot actually be exploited in my project) but I also like the slog-term crate, so if you want me to take over this PR and fix the once-cell issues I can do that.

[rkday-pro]

This doesn't quite work even with the once_cell issues fixed - https://github.com/sunfishcode/is-terminal/blob/main/Cargo.toml depends on rustix which depends on bitflags 2.3.3, which also has edition = 2021 (https://github.com/bitflags/bitflags/blob/main/Cargo.toml).

This might need an MSRV bump - is_terminal has an MSRV of 1.63 and that's the lowest bump I could make work.

#47 makes that bump on top of these commits.

[Techcable]

Merged #47, which supersedes this PR.