Bumps [actions/cache](https://github.com/actions/cache) from 5 to 6.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@v5...v6)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Removed 'amazonlinux2' from the list of Linux OS versions.

Amazon Linux 2023 reports ID=amzn and VERSION_ID=2023 in
/etc/os-release. This combination fell through to the generic
else branch, producing the OS name amzn2023 and thus an invalid
Swift toolchain download URL (swift-...-amzn2023-aarch64.tar.gz),
causing a "Toolchain not found" failure. Special-case it to the
amazonlinux2023 infix that swift.org actually publishes.

In version 0.0.11, the ADDITIONAL_DOCC_ARGUMENTS environment variable is
supported by the check-docs.sh script.  Version 0.0.12 modified the
check-docs.sh was updated in version 0.0.12 to not depend on the
environment variable.  However, this caused a regression for worlflows
that were still using 0.0.11 as the defined environment variable was no
longer being used.

Update the check-docs.sh script to default the additional_docc_argument
to the environment variable.

The yq expression used to read documentation targets from .spi.yml wrapped
the config in select(.documentation_targets[] != ""). Because the filter
inside select() evaluates .documentation_targets[] as a stream of booleans,
select() re-emits the config once per target, and the trailing
.documentation_targets[] then multiplies the list to N*N entries.

For a package with 17 doc targets this expanded to ~272 targets, so
check-docs.sh built every target ~17 times and the job hit its 20 minute
timeout (appearing to hang / infinite loop).

Move the empty-string guard onto each individual target so every target is
emitted exactly once.