changed context typing to also accept string as device - and tested i…

[PhiSpel]

Description

closes #223

Checklist

• [x] This pull request is associated to an issue
• [x] This PR contains a description
• [x] ~Did you add a new method? If so, you need to~
  • [x] ~add method description~
  • [x] ~maybe mention class in the corresponding __init__~
  • [x] ~add an example using the method in examples/advanced_flows/ or examples/simple_flows/~
  • [x] ~add a test in tests/~
• [x] Add someone else as reviewer and wait for approval before merging.