Remove Optional and Union type hint

[andchiind]

Closes #1090

Depends on #1085

This complies with the python best practise https://typing.python.org/en/latest/reference/best_practices.html#shorthand-syntax

Ready for review checklist:

• A self-review has been performed
• All commits run individually
• Temporary changes have been removed, like logging, TODO, etc.
• The PR has been tested locally
• A test has been written
  • This change doesn't need a new test
• Relevant issues are linked
• Remaining work is documented in issues
  • There is no remaining work from this PR that requires new issues
• The changes do not introduce dead code as unused imports, functions etc.

[github-actions]

This pull request has been automatically marked as stale due to inactivity.