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.yml

@@ -91,7 +91,7 @@ jobs:
     - name: Coursier cache
       uses: coursier/cache-action@v6
     - name: Cache sbt
-      uses: actions/cache@v2.1.6
+      uses: actions/cache@v2.1.7
       with:
         path: ~/.sbt
         key: ${{ runner.os }}-sbt-cache-${{ hashFiles('**/*.sbt') }}-${{ hashFiles('project/build.properties') }}