chore(deps): bump actions/cache from 2.1.5 to 2.1.6 (#2020)

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](https://github.com/actions/cache/compare/v2.1.5...v2.1.6)

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Frederic Werner <20406381+wernerfred@users.noreply.github.com>
Co-authored-by: Georg Lauterbach <44545919+aendeavor@users.noreply.github.com>

.github/workflows/default_on_push.yml

@@ -26,7 +26,7 @@ jobs:
         uses: docker/setup-buildx-action@v1.3.0
         id: buildx
       - name: Cache Docker layers
-        uses: actions/cache@v2.1.5
+        uses: actions/cache@v2.1.6
         with:
           path: /tmp/.buildx-cache
           key: ${{ runner.os }}-buildx-${{ github.sha }}
@@ -80,7 +80,7 @@ jobs:
         uses: docker/setup-buildx-action@v1.3.0
         id: buildx
       - name: Cache Docker layers
-        uses: actions/cache@v2.1.5
+        uses: actions/cache@v2.1.6
         with:
           path: /tmp/.buildx-cache
           key: ${{ runner.os }}-buildx-${{ github.sha }}

.github/workflows/test_merge_requests.yml

@@ -25,7 +25,7 @@ jobs:
         uses: docker/setup-buildx-action@v1.3.0
         id: buildx
       - name: Cache Docker layers
-        uses: actions/cache@v2.1.5
+        uses: actions/cache@v2.1.6
         with:
           path: /tmp/.buildx-cache
           key: ${{ runner.os }}-buildx-${{ github.sha }}