cmp is a string already. Therefore, the join() statement is not necessary
and only introduces additional spaces.

The `blockdevice` module raises a `RuntimeError` if `blockdev` returns with a
non-zero exit code, or if stderr is not empty.

But the latter can happen even when there's no failure at all, for instance if
`sshd` has a banner message configured (which gets output to stderr whenever
someone connects to the host).

Signed-off-by: Benoît Knecht <bknecht@protonmail.ch>

The old implementation limits the usage of SystemdService.is_valid() to
".service" units. This implementation allows checking all types of unit
files with is_valid() (systemd-analyze verify <unitname.suffix>).

Fixes #736.

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Added "ol" Oracle Linux and moved "rhel" accordingly

---------

Co-authored-by: 100gr <v.aukhimovich@gmail.com>