Release 12.1

> How to

Before merge

On the 22nd, a few minutes before merging this and before the scheduled pipeline runs:

1. Un-WIP and merge 12.1 dropdown !493 (merged). This will update run the pipeline for 12.1 and update the Docker image.
2. Un-WIP and merge 12.0 dropdown !494 (merged). This will update run the pipeline for 12.0 and update the Docker image.
3. Un-WIP and merge 11.11 dropdown !495 (merged). This will update run the pipeline for 11.11 and update the Docker image.
4. Once all above pipelines are green, it's time to merge this MR.

After merge

1. Manually run the scheduled pipeline.