add celery library to api-server

Author: bisgaard-itis

services/api-server/requirements/_base.in

@@ -7,6 +7,7 @@
 --constraint ./constraints.txt
 
 # intra-repo required dependencies
+--requirement ../../../packages/celery-library/requirements/_base.in
 --requirement ../../../packages/common-library/requirements/_base.in
 --requirement ../../../packages/models-library/requirements/_base.in
 --requirement ../../../packages/postgres-database/requirements/_base.in