Error messages when running zairachem without GPU (usability issue)

[marcostorrework]

Describe the bug
When using a computer without a GPU, every time that the zairachem CLI command is run, several lines of (harmless) errors are displayed. See screenshot.
This is just a usability issue, as it does not prevent the tool from working.

To Reproduce
Steps to reproduce the behavior:
In a computer without GPU, run the zairachem CLI command, with any options. The errors appear at the beginning.

Expected behavior
It would be a better user experience to remove these error messages and instead show a warning, something like "Warning: no GPU available - Zairachem can still be used but some of the models will require longer training time."

Screenshots

Desktop (please complete the following information):

• OS: Linux Ubuntu 20.04

[miquelduranfrigola]

As we are preparing the ZairaChem release, all of this will be solved. Well noted, thanks.