switch singleuser base image for arm tests

chartpress doesn't support multiple base images,
but real deployments won't use the sample image anyway

Author: minrk

.circleci/config.yml

@@ -50,6 +50,14 @@ jobs:
             pip3 install --no-cache-dir -r dev-requirements.txt
           name: Install dependencies
 
+      - run:
+          name: fix singleuser base image for aarch64
+          # Jupyter docker-stacks don't have multi-arch images
+          # see https://github.com/jupyterhub/zero-to-jupyterhub-k8s/issues/2844
+          command: |
+            sed -i -E s@base-notebook:latest@base-notebook:aarch64-latest@ images/singleuser-sample/Dockerfile
+            git diff
+
       - run:
           command: |
             chartpress