github-actions(deps): bump actions/cache from 2.1.5 to 2.1.6

Bumps [actions/cache](https://github.com/actions/cache) from 2.1.5 to 2.1.6.
- [Release notes](https://github.com/actions/cache/releases)
- [Commits](actions/cache@v2.1.5...v2.1.6)

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

Author: dependabot[bot]

.github/workflows/tests.yml

@@ -32,7 +32,7 @@ jobs:
               run: echo "::set-output name=dir::$(composer config cache-files-dir)"
 
             - name: Cache dependencies
-              uses: actions/cache@v2.1.5
+              uses: actions/cache@v2.1.6
               with:
                   path: ~/.composer/cache/files
                   key: dependencies-laravel-${{ matrix.laravel }}-php-${{ matrix.php }}-composer-${{ hashFiles('composer.json') }}