Update the CI to run on auto-built images

I noticed that one of the jobs had failed to pull the image, I retried and it looked like it worked. It's a little concerning that one of the jobs failed in the first set.

I had forgotten to build the py38 image first time round. The first build is manual. I need to check that it links up properly,but I'll double-check that this eve

changed milestone to %1.1.0

This is now ready to go. FWIW, I've confirmed the new images are being built:

added Infrastructure Testing labels

approved this merge request

approved this merge request

merged

mentioned in commit 9affbf04

mentioned in merge request !928 (merged)