This pull request adds new GitHub Actions for installing `cosign` and
`syft`, and updates the CI, release, and security workflows.
**New Actions:**
- [`install-cosign`](.github/actions/install-cosign/action.yaml):
Installs `cosign` with a configurable version.
- [`install-syft`](.github/actions/install-syft/action.yaml): Installs
`syft` with a configurable version.
**Workflow Updates:**
- CI, release, and security workflows now use `install-cosign` and
`install-syft`.
M Atif Ali