`keccak` was previously excluded from the toplevel workspace due to its
MSRV of 1.41 and incompatibilities with packages used by `ascon`.
This bumps the edition, changes the version to `0.2.0-pre` to denote it
contains breaking changes (though this is not intended to be a
`0.2.0-pre` release), and bumps MSRV.
With the MSRV bumped, `keccak` can and has been re-added to the toplevel
workspace.
`mips-unknown-linux-gnu` is now a Tier 3 target: rust-lang/rust#115218.
This means we can't use it for cross tests anymore since std is no
longer built for it.
This commit replaces it with `powerpc-unknown-linux-gnu`, a big endian
Tier 2 target.
Basically all of the `actions-rs/*` actions are unmaintained. See
<https://github.com/actions-rs/toolchain/issues/216> for more
information. Due to their age they generate several warnings in
CI runs.
To get rid of those warnings the occurrences of
`actions-rs/toolchain` are replaced by `dtolnay/rust-toolchain`,
and the occurrences of `actions-rs/cargo` are replaced by direct
invocations of `cargo`.
`packed_simd_2` no longer builds on nightly:
https://github.com/rust-lang/packed_simd/issues/343
This commit pins the nightly version for now, and disables the
`minimal-versions` check since it's not customizable and requires the
latest nightly.
