Bump actions/cache from 2.1.5 to 2.1.6

Bumps [actions/cache](https://github.com/actions/cache) from 2.1.5 to 2.1.6.
- [Release notes](https://github.com/actions/cache/releases)
- [Commits](actions/cache@v2.1.5...v2.1.6)

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

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -60,7 +60,7 @@ jobs:
         with:
           driver-opts: network=host
       - name: Cache Docker layers
-        uses: actions/[email protected].5
+        uses: actions/[email protected].6
         with:
           path: /tmp/.buildx-cache
           key: ${{ runner.os }}-buildx-${{ github.sha }}
@@ -123,7 +123,7 @@ jobs:
         with:
           driver-opts: network=host
       - name: Cache Docker layers
-        uses: actions/[email protected].5
+        uses: actions/[email protected].6
         with:
           path: /tmp/.buildx-cache
           key: ${{ runner.os }}-buildx-${{ github.sha }}