For consistency with the new templates. The top-level README was moved
under the `bazelisk` component.

Leftover from 29e2a546.

The default only made sense for the `ruleset` template. When using the
`semantic-release` in isolation, an empty array is a better default.

It also seeems that `os` was missing, which is likely leftover from
0fe682fc.

We now have a MacOS test runner to validate our rulesets.

Prevents conflicting cache ACLS.

The `input:oses` can be set to an array of operating systems
to test each job on.

By default, Linux and Windows are tested.

Makes sure that caches on Linux, Mac, Windows do not conflict.

BREAKING CHANGE: `minimum` is no longer an input to the `ruleset` component. Use `versions` instead.

BREAKING CHANGE: The `ruleset` component `needs` input is now dependent tasks for the testing jobs. Previously it was for the `semantic-release` job which was not useful.

Still need to use them.

`after_script` was failing with "DST: unbound variable", which was
causing the artifacts to not be uploaded.

Needed for the fragments to work correctly.

Not available in some Shells.

Accidentally changed it whilst testing.

We use a cache key that is instance wide.

Be safe and only cache what we expect.

Upgrades all other dependencies and the base image.