chore: set MSRV to 1.66 and edition to 2021

[weihanglo]

Some new API were already used

• format arg capture (1.58)
• std::os::fd (1.66)

A bump is inevitably coming.

[weihanglo]

@petrochenkov, do you know who's the owner of this repo, and how the release process look like?

[petrochenkov]

@weihanglo
I can publish new versions of this crate now.

[petrochenkov]

Could you add a CI check for the minimum supported version?
Example: https://github.com/mozilla/cbindgen/blob/master/.github/workflows/cbindgen.yml#L32-L38

[weihanglo]

Updated. Let me know if it is too excessive, and we can slim it down a bit.

[petrochenkov]

Tests are hanging since yesterday, so something is probably wrong with CI changes (missing -latest on macos and windows?).

[weihanglo]

Embarrassing 😆.

@petrochenkov, just updated. Thank you for the catch.