Bump actions/cache from v1 to v2.1.4

Bumps [actions/cache](https://github.com/actions/cache) from v1 to v2.1.4.
- [Release notes](https://github.com/actions/cache/releases)
- [Commits](actions/cache@v1...26968a0)

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

.github/workflows/main.yml

@@ -21,7 +21,7 @@ jobs:
       run: go mod download
 
     - name: Cache modules
-      uses: actions/cache@v1
+      uses: actions/cache@v2.1.4
       with:
         path: ~/go/pkg/mod
         key: ${{ runner.OS }}-go-${{ hashFiles('**/go.sum') }}