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/prettier.yml

@@ -6,7 +6,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - uses: actions/cache@v1
+      - uses: actions/cache@v2.1.4
         with:
           path: ~/.npm
           key: npm-${{ hashFiles('**/package-lock.json') }}