Bug 17086: Reword borrowers to patrons in Swagger tags for holds

Bug 17086: Reword borrowers to patrons in Swagger tags for holds

Routes for holds have tags called "borrowers". We should use "patrons" instead
in order not to have both (endpoints for patrons already add "patrons").

This patch changes the tags from borrowers to patrons in:
GET  /holds
POST /holds

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Katrin Fischer  <katrin.fischer@bsz-bw.de>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>