fix(druid): import pydruid.db module explicitly (#8782)

ibis/backends/druid/__init__.py

@@ -7,7 +7,7 @@
 from typing import TYPE_CHECKING, Any
 from urllib.parse import parse_qs, urlparse
 
-import pydruid
+import pydruid.db
 import sqlglot as sg
 
 import ibis.common.exceptions as com