Bump actions/cache from 1 to 2.1.6 (#3)

Bumps [actions/cache](https://github.com/actions/cache) from 1 to 2.1.6.
- [Release notes](https://github.com/actions/cache/releases)
- [Commits](https://github.com/actions/cache/compare/v1...v2.1.6)

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

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/test.yaml

@@ -14,7 +14,7 @@ jobs:
           go-version: ${{ matrix.go-version }}
       - name: Checkout code
         uses: actions/checkout@v2.3.4
-      - uses: actions/cache@v1
+      - uses: actions/cache@v2.1.6
         with:
           path: ~/go/pkg/mod
           key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}