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/ci.yml

@@ -27,7 +27,7 @@ jobs:
       - uses: actions/setup-python@v2
       - uses: actions/checkout@v2
       - run: sudo apt install -y gettext aspell libenchant-dev
-      - uses: actions/[email protected].4
+      - uses: actions/[email protected].5
         with:
           path: ~/.cache/pip
           key: ${{ runner.os }}-pip-${{ hashFiles('lint-requirements.txt') }}
@@ -50,7 +50,7 @@ jobs:
     steps:
       - uses: actions/setup-python@v2
       - uses: actions/checkout@v2
-      - uses: actions/[email protected].4
+      - uses: actions/[email protected].5
         with:
           path: ~/.cache/pip
           key: ${{ runner.os }}-pip-${{ hashFiles('lint-requirements.txt') }}