Update an item

[ALHelton]

This endpoint should:

• update the corresponding Item (if found) with whichever details are provided by the user
• render a JSON representation of the updated record.
• follow this pattern: PATCH /api/v1/items/:id
• accept the following JSON body with one or more of the following fields: The body should follow this pattern:

(Note that the unit price is to be sent as a numeric value, not a string.)

Example JSON response for the Item resource:

[ALHelton]

Need to do sad path testing