use maintainer tools action

Author: blink1073

.github/actions/test-downstream/action.yml

@@ -18,29 +18,29 @@ jobs:
         uses: jupyterlab/maintainer-tools/.github/actions/base-setup@v1
 
       - name: Test IPykernel
-        uses: ./.github/actions/test-downstream
+        uses: jupyterlab/maintainer-tools/.github/actions/downstream-test@v1
         with:
           package_name: ipykernel
           package_spec: "pyqt5 ipykernel[test]"
 
       - name: Test NBClient
-        uses: ./.github/actions/test-downstream
+        uses: jupyterlab/maintainer-tools/.github/actions/downstream-test@v1
         with:
           package_name: nbclient
           env_values: IPYKERNEL_CELL_NAME=\<IPY-INPUT\>
 
       # Note: Currently fails
       # - name: Test QtConsole
-      #   uses: ./.github/actions/test-downstream
+      #   uses: jupyterlab/maintainer-tools/.github/actions/downstream-test@v1
       #   with:
       #     package_name: qtconsole
 
       - name: Test nbconvert
-        uses: ./.github/actions/test-downstream
+        uses: jupyterlab/maintainer-tools/.github/actions/downstream-test@v1
         with:
           package_name: nbconvert
 
       - name: Test jupyter_server
-        uses: ./.github/actions/test-downstream
+        uses: jupyterlab/maintainer-tools/.github/actions/downstream-test@v1
         with:
           package_name: jupyter_server