Add yarn dependency caching to GHA workflow

Signed-off-by: Laura Brehm <laurabrehm@hey.com>

Author: laurazard

.github/workflows/ci.yml

@@ -16,5 +16,6 @@ jobs:
       - uses: actions/setup-node@v3
         with:
           node-version: 16
+          cache: 'yarn'
       - run: yarn install --frozen-lockfile
       - run: yarn test