CI: Pin conda in docker build
- [x] xref #48142

This gets ci green for now, but have to investigate what is wrong here. The first failing build updated conda from 4.13 to 4.14 with the ``conda install mamba``  command, hence the pin there

cc @mroeschke 
Not sure. We are using micromamba for most builds, so should not. I'll open a pr in parallel to check if we can switch to mambaforge as base image here. This should solve this. > Not sure. We are using micromamba for most builds, so should not. I'll open a pr in parallel to check if we can switch to mambaforge as base image here. This should solve this.

Sounds good. Switching to micromamba would probably be a preferred fix here. Yep agreed. This is only a temporary solution to get the ci passing agai anyway #48143 uses mambaforge as base image. Gets the ci back to green too > #48143 uses mambaforge as base image. Gets the ci back to green too

is that the preference? and close this one? > > #48143 uses mambaforge as base image. Gets the ci back to green too
> 
> is that the preference? and close this one?

Yes, that would be my preference. Yep, let’s merge the other pr 