Add Printful API to Shopping

[DiterDise]

• [x] My submission is formatted according to the guidelines in the contributing guide
• [x] My addition is ordered alphabetically
• [x] My submission has a useful description
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• [x] Each table column is padded with one space on either side
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• [x] Any category I am creating has the minimum requirement of 3 items
• [x] All changes have been squashed into a single commit