build(deps): bump actions/checkout from 3.5.3 to 3.6.0 (#39617)

Bumps [actions/checkout](https://github.com/actions/checkout) from 3.5.3 to 3.6.0.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](c85c95e3d7...f43a0e5ff2)

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

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

.github/workflows/build-containers.yml

@@ -56,7 +56,7 @@ jobs:
     if: github.repository == 'spack/spack'
     steps:
       - name: Checkout
-        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # @v2
+        uses: actions/checkout@f43a0e5ff2bd294095638e18286ca9a3d1956744 # @v2
 
       - name: Set Container Tag Normal (Nightly)
         run: |