enable pyscopg2 unicode type caster (#30752)

Facilitate SELECT query with a WHERE clause
on a varchar column.

wcs_olap/feeder.py

@@ -260,6 +260,8 @@ class WcsOlapFeeder(object):
         self.connection = psycopg2.connect(dsn=pg_dsn)
         self.connection.autocommit = True
         self.cur = self.connection.cursor()
+        psycopg2.extensions.register_type(psycopg2.extensions.UNICODE, self.cur)
+
         try:
             self.has_jsonb = self.detect_jsonb()
             if self.has_jsonb: