Pysilpo

Changelog:
* fix: Rewrite substract_months function, added unittests for it

**Full Changelog**: https://github.com/iYasha/pysilpo/compare/v1.0.1...v1.0.2

Changelog:
- fix: Added retry mechanism and cache invalidation for User.login method in case cache data expired

**Full Changelog**: https://github.com/iYasha/pysilpo/compare/v1.0.0...v1.0.1

What's new
- Implemented Silpo Product API to fetch products
- Added Cursor for better and pythonic experience
- Implemented City and Store APIs to fetch store information

Changelog
- Fix cannot import UTC in python3.9

**Full Changelog**: https://github.com/iYasha/pysilpo/compare/v0.2.0...v0.2.1

What's Changed
* Added OpenID OTP authorization support with cached session and token refresh mechanism
* Cheque API now more clear and using RestFul API
* Debug mode now supported!


**Full Changelog**: https://github.com/iYasha/pysilpo/compare/v0.1.2...v0.2.0

What's Changed
* fix: `APIClient.get` might return None by iYasha in https://github.com/iYasha/pysilpo/pull/4


**Full Changelog**: https://github.com/iYasha/pysilpo/compare/v0.1.1...v0.1.2