Fix TempId.__hash__ to follow python rules

[manuelma]

The idea here is that TempId.__hash__ plays well with TempId.__eq__ as per the Python spec, to avoid all kinds of bugs down the line.

Checklist before merging

• [x] Documentation (also in Toolbox repo) is up-to-date
• [x] Release notes in Toolbox repo have been updated
• [x] Unit tests have been added/updated accordingly
• [x] Code has been formatted by black
• [x] Unit tests pass