build(deps): bump actions/cache from v2.1.4 to v2.1.5 (golangci#1918)

Bumps [actions/cache](https://github.com/actions/cache) from v2.1.4 to v2.1.5.
- [Release notes](https://github.com/actions/cache/releases)
- [Commits](actions/cache@v2.1.4...1a9e213)

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

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

Author: dependabot[bot]

.github/workflows/pr.yml

@@ -75,7 +75,7 @@ jobs:
         uses: actions/setup-go@v2
         with:
           go-version: ${{ matrix.golang }}
-      - uses: actions/[email protected].4
+      - uses: actions/[email protected].5
         with:
           path: ~/go/pkg/mod
           key: ${{ runner.os }}-go-${{ matrix.golang }}-${{ hashFiles('**/go.sum') }}