The `rust` tool was resolved via the `github-tags` datasource on
`rust-lang/rust` with the default (semver) versioning. That meant the
release channel values rustup actually accepts were not understood.
Switch all three managers to the `rust-version` datasource, which
declares `rust-release-channel` as its `defaultVersioning`, matching the
`rust-toolchain` manager and `lib/util/exec/containerbase.ts`.
`packageName` becomes `rust` rather than the `rust-lang/rust` owner/repo
slug, which is meaningless for this datasource. It is set rather than
omitted because mise would otherwise fall back to the backend-prefixed
depName, yielding `core:rust` / `asdf:rust` as the package name.
No explicit `versioning` is set: the datasource default already applies,
and the convention in these files is to set `versioning` only to
override a datasource default.
Behaviour change: `nightly-<date>` pins were previously skipped as
`invalid-value` and now update. `stable`, `beta` and `nightly` are now
recognised as ranges rather than flagged invalid, but still only resolve
to a concrete version under `rangeStrategy: pin`.
Sebastian Poxhofer