models:update pos & product

[LaDen2]

Changes to pos & product model

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Description

<!--- Add some new fields to the pos model like total_amount,method_of_payment and also set the relationship to one to many(Transaction-->Product) so that one transaction can include many products but one product can be include in one transaction only!

Motivation and Context

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How Has This Been Tested?

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Types of changes

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• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] Chore (improves application but is not new functionality nor a bug fix)

Checklist:

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• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.

[LaDen2]

Merged, error with Pip, must solve it later!