fix(duckdb): gate geoalchemy import in duckdb geospatial

ibis/backends/duckdb/registry.py

@@ -6,7 +6,6 @@
 
 import numpy as np
 import sqlalchemy as sa
-from geoalchemy2 import Geometry
 from sqlalchemy.ext.compiler import compiles
 from sqlalchemy.sql.functions import GenericFunction
 
@@ -29,6 +28,18 @@
 )
 from ibis.common.exceptions import UnsupportedOperationError
 
+try:
+    from geoalchemy2 import Geometry
+
+    class Geometry_WKB(Geometry):
+        as_binary = "ST_AsWKB"
+
+except ImportError:
+
+    class Geometry_WKB:
+        ...
+
+
 if TYPE_CHECKING:
     from collections.abc import Mapping
 
@@ -56,10 +67,6 @@ def _round(t, op):
 }
 
 
-class Geometry_WKB(Geometry):
-    as_binary = "ST_AsWKB"
-
-
 def _centroid(t, op):
     arg = t.translate(op.arg)
     return sa.func.st_centroid(arg, type_=Geometry_WKB)