fix: convert project_id to string

[NiklasKoehneckeAA]

Description

No description.

Before Merging

• Review the code changes
  • Unused print / comments / TODOs
  • Missing docstrings for functions that should have them
  • Consistent variable names
  • ...
• Update changelog.md if necessary
• Commit messages should contain a semantic label and the ticket number
  • Consider squashing if this is not the case

[MerlinKallenbornAA]

I will take care of this as soon as the functionalities in Studio are done

[maxhammeralephalpha]

@MerlinKallenbornAA @maxhammeralephalpha
Check whether we need to convert project to str in other resources as well, e.g. trace, datasets etc.