fix for failing CI

[olelod]

A new fix due to complaints from the latest mypy version

---

Contributor checklist

• [ ] :tada: This PR closes #ISSUE_NUMBER.
• [ ] :scroll: I have broken down my PR into the following tasks:
  • [ ] Task 1
  • [ ] Task 2
• [ ] :robot: I have added tests, or extended existing tests, to cover any new features or bugs fixed in this PR.
• [ ] :book: I have considered adding a new entry in CHANGELOG.md.
• [ ] :books: I have considered updating the documentation.