Building and pushing images can fail with network errors

[scottyhq]

#426

passed tests, but then when merged into main failed due to network errors running apt-get:

#9 1125.5 E: Failed to fetch http://archive.ubuntu.com/ubuntu/pool/main/i/icu/libicu70_70.1-2_amd64.deb Error reading from server. Remote end closed connection

https://github.com/pangeo-data/pangeo-docker-images/actions/runs/3907761598

Can manually re-trigger but these failures could be easy to overlook. A more robust CI strategy could be to simply retag built images from the PR...

[yuvipanda]

We could have an automatic retry maybe on failure?