[DIN-749] Add feature to delete nulls in overrides

[Miller-GS]

Why? 📖

There is currently no way to remove a key that was previously added using overrides. This is a limitation that we can solve by removing null values.

What? 🔧

• Add feature to remove key if the value in the override is None
• Add unit test for new case
• Update version to 1.0.4

Type of change 🗄️

• New feature (non-breaking change which adds functionality)

How everything was tested? 📏

Unit tests

Checklist 📝

• I have added labels to distinguish the type of pull request.
• My code follows the style guidelines of this project (docstrings, type hinting and linter compliance);
• I have performed a self-review of my own code;
• I have made corresponding changes to the documentation;
• I have added tests that prove my fix is effective or that my feature works;
• I have made sure that new and existing unit tests pass locally with my changes;

[sonarcloud]

Quality Gate passed

The SonarCloud Quality Gate passed, but some issues were introduced.

1 New issue
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud

[dutrevis]

Would we want to choose wether the key is removed or it's persisted with the None value? There may be some situations where we would like to keep the key with the None, or am I being to picky?