Al/fix gpu index

[agnesLeroy]

closes: please link all relevant issues

PR content/description

Check-list:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• Relevant issues are marked as resolved/closed, related issues are linked in the description
• Check for breaking changes (including serialization changes) and add them to commit message following the conventional commit specification

[pdroalves]

Finally a easy one to review :-D

This one is only changing variable names (stream => streams) and asserting we use the first active gpu index instead of 0, right? If so, we are god to go.