Try with node 12

Author: jtpio

.github/workflows/tests.yml

@@ -169,7 +169,7 @@ jobs:
     - name: Set up Node
       uses: actions/setup-node@v2
       with:
-        node-version: 14.x
+        node-version: 12.x
 
     - name: Get yarn cache
       id: yarn-cache
@@ -249,4 +249,4 @@ jobs:
       uses: actions/upload-artifact@v2
       with:
         name: ipywidgets-updated-snapshots
-        path: ui-tests/tests
+        path: ui-tests/tests