build(deps): Bump actions/cache from v2.1.4 to v2.1.5 (#60)

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] <support@github.com>

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

Author: dependabot[bot]

.github/workflows/pull_request.yml

@@ -19,7 +19,7 @@ jobs:
 
     - name: Cache pip
       id: cache
-      uses: actions/cache@v2.1.4
+      uses: actions/cache@v2.1.5
       with:
         path: ~/.cache/pip
         key: ${{ runner.os }}-pip-${{ hashFiles('requirements.txt') }}