change to foreign key for currencies

[todo]

online-store-rest-api/online_store/backend/models/item.py

Lines 41 to 46 in cf11f6f

	currency = Column(Text) # TODO: change to foreign key for currencies
	in_stock_quantity = Column(Integer, nullable=False)
	@classmethod
	def load_json(cls, filepath: Union[Path, str]):
	"""Convenience method for loading JSON data into items table."""

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This issue was generated by todo based on a TODO comment in cf11f6f when #12 was merged. cc @Liam-Deacon.