build(deps): bump actions/cache from 2.1.6 to 2.1.7

Bumps [actions/cache](https://github.com/actions/cache) from 2.1.6 to 2.1.7.
- [Release notes](https://github.com/actions/cache/releases)
- [Commits](https://github.com/actions/cache/compare/v2.1.6...v2.1.7)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

.github/workflows/ci.yaml

@@ -169,7 +169,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2.4.0
       - name: Stack working files cache
-        uses: actions/cache@v2.1.6
+        uses: actions/cache@v2.1.7
         with:
           path: ${{ matrix.cache }}
           key: ${{ runner.os }}-${{ hashFiles('stack.yaml.lock') }}