Take ownership of conda on Azure Mac builds

[leouieda]

Some builds were failing because of permission issues for conda. Adding
this seems to solve those problems.

Fixes the issues in #78

Reminders

• Run make format and make check to make sure the code follows the style guide.
• Add tests for new features or tests that would have caught the bug that you're fixing.
• Add new public functions/methods/classes to doc/api/index.rst.
• Write detailed docstrings for all functions/methods.
• If adding new functionality, add an example to the docstring, gallery, and/or tutorials.

[leouieda]

@santisoler if the CI gods are happy with my sacrifice, please feel free to merge this