CI: use custom (better) Yarn cache strategy

See: actions/setup-node#325

.github/workflows/continuous-integration-javascript.yml

@@ -29,7 +29,19 @@ jobs:
         uses: actions/[email protected]
         with:
           node-version: ${{ matrix.node-version }}
-          cache: 'yarn'
+
+      - name: Get Yarn cache directory path
+        id: yarn-cache-dir-path
+        run: echo "::set-output name=dir::$(yarn config get cacheFolder)"
+
+      # https://github.com/actions/cache
+      - name: Restore Yarn cache
+        uses: actions/[email protected]
+        with:
+          path: ${{ steps.yarn-cache-dir-path.outputs.dir }}
+          key: yarn-cache-folder-${{ hashFiles('**/yarn.lock', '.yarnrc.yml') }}
+          restore-keys: |
+            yarn-cache-folder-
 
       - name: Install Yarn dependencies
         run: yarn install --immutable