fix(typings): Python 3.8 defaultdict

[DavidVujic]

Description

Fixes an issue with Python 3.8 and missing typings for DefaultDict.

Motivation and Context

To fix failing CI build for Python 3.8.

How Has This Been Tested?

Local test runs.
CI ✅

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• I have read the code of conduct.
• I have read the contributing guide.
• I have updated the documentation accordingly (if applicable).

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[BeRT2me]

@DavidVujic If you add this to your mypy.ini, it'll catch these :)

[mypy]
python_version = 3.8

---

from __future__ import annotations would be another option as well https://mypy.readthedocs.io/en/stable/runtime_troubles.html#future-annotations-import-pep-563

[DavidVujic]

I'll do that! 😄