Adding the following changes:
- using mypy to find typing errors
- used pylint to find other small errors
- added pylint and mypy to pipeline
What's Changed
* Typing refactor by tybruno in https://github.com/tybruno/modifiable-items-dictionary/pull/23
**Full Changelog**: https://github.com/tybruno/modifiable-items-dictionary/compare/v3.0.1...v3.0.2