Add yarn

.github/workflows/test.yml

@@ -47,6 +47,22 @@ jobs:
         with:
           node-version: 14.17.5
 
+      - name: Find yarn cache location
+        id: yarn-cache
+        run: echo "::set-output name=dir::$(yarn cache dir)"
+
+      - name: JS package cache
+        uses: actions/cache@v4
+        with:
+          path: ${{ steps.yarn-cache.outputs.dir }}
+          key: ${{ runner.os }}-yarn-${{ hashFiles('**/yarn.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-yarn-
+
+      - name: Install packages
+        run: |
+          yarn install --pure-lockfile
+
       - name: Precompile assets
         run: bin/rails assets:precompile