Fixing `collections` import
Hi @fbeninca,
As discussed in https://github.com/ESMValGroup/ESMValTool/pull/2184, the import from collections import Iterable
has to be updated to from collections.abc import Iterable
since Python 3.3 . I will open a merge request to take these changes into account.
This changes should also be updated to pypi, as ESMValTool installs the package from there.