Bump reproducible-containers/buildkit-cache-dance from 2.1.2 to 2.1.4

Bumps [reproducible-containers/buildkit-cache-dance](https://github.com/reproducible-containers/buildkit-cache-dance) from 2.1.2 to 2.1.4.
- [Release notes](https://github.com/reproducible-containers/buildkit-cache-dance/releases)
- [Commits](reproducible-containers/buildkit-cache-dance@v2.1.2...v2.1.4)

---
updated-dependencies:
- dependency-name: reproducible-containers/buildkit-cache-dance
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/docker.yml

@@ -45,17 +45,17 @@ jobs:
           path: cargo
           key: cargo-${{ hashFiles('Containerfile') }}
       - name: Inject var-cache-apt into Docker
-        uses: reproducible-containers/[email protected].2
+        uses: reproducible-containers/[email protected].4
         with:
           cache-source: var-cache-apt
           cache-target: /var/cache/apt
       - name: Inject var-lib-apt into Docker
-        uses: reproducible-containers/[email protected].2
+        uses: reproducible-containers/[email protected].4
         with:
           cache-source: var-lib-apt
           cache-target: /var/lib/apt
       - name: Inject cargo into Docker
-        uses: reproducible-containers/[email protected].2
+        uses: reproducible-containers/[email protected].4
         with:
           cache-source: cargo
           cache-target: /code/boys/target