circulation: fix patron barcode

[Garfield-fr]

Code review check list

• Commit message template compliance.
• Commit message without typos.
• File names.
• Functions names.
• Functions docstrings.
• Unnecessary commited files?
• Cypress tests successful?

[zannkukai]

In our consortium, patrons could have multiple barcodes. This is why barcode field is an array.
Using your changes, it should be failed ? Isn't it ?

[Garfield-fr]

In our consortium, patrons could have multiple barcodes. This is why barcode field is an array. Using your changes, it should be failed ? Isn't it ?

The API now returns only the first barcode, because in the code we always did [0].