Bug 29810: Fix patron embed definitions

Due to a race and a bad rebase, the patrons embeds added on bug 30063
didn't get copied to the parameters secition, thus breaking embedding.

To test:
1. In master, open the patron search page and the inspector
2. Perform a search
=> FAIL: No results
=> FAIL: There's an error 500 in the API response, mentioning embedding
is not allowed
3. Apply this patch
4. Restart all
6. Repeat 2
=> SUCCESS: Results are back!
=> SUCCESS: No more API errors
7. Sign off :-D

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>

api/v1/swagger/paths/patrons.yaml

@@ -361,6 +361,9 @@
           type: string
           enum:
             - extended_attributes
+            - checkouts+count
+            - overdues+count
+            - account_balance
         collectionFormat: csv
     responses:
       "200":