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

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](https://github.com/actions/cache/compare/v2.1.4...1a9e2138d905efd099035b49d8b7a3888c653ca8)

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

.github/workflows/build.yml

@@ -106,7 +106,7 @@ jobs:
       cache-version: v1
     steps:
       - uses: actions/checkout@v2
-      - uses: actions/cache@v2.1.4
+      - uses: actions/cache@v2.1.5
         with:
           path: ${{ env.package-dir }}
           key: ${{ runner.os }}-cygwin-${{ env.cache-version }}