github-actions(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](actions/cache@v2.1.4...1a9e213)

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

Author: dependabot[bot]

.github/workflows/tests_php.yml

@@ -22,7 +22,7 @@ jobs:
         run: echo "::set-output name=dir::$(composer config cache-files-dir)"
 
       - name: Cache dependencies
-        uses: actions/[email protected].4
+        uses: actions/[email protected].5
         with:
           path: ~/.composer/cache/files
           key: dependencies-php-${{ matrix.php }}-composer-${{ hashFiles('composer.json') }}