Make CI on macOS pass

[fabern]

With the merging of #70, CI is still failing on macOS.
This is linked to an old system package that is installed before gdal: proj@7.
Having this fixed might be low priority. In case we want to do it the following is needed:

We might need to update or remove installation of gdal in the workflow file here.

Do we have another package with rgdal dependency we could copy?

[fabern]

As per stineb's answer here: #70 (comment)

We'll be eventually phasing out {rgdal} in favor of {terra}.