Update samples/snippets/requirements.txt

Author: chalmerlowe

samples/snippets/requirements.txt

@@ -1,7 +1,8 @@
 alembic==1.16.4;  python_version >= '3.9'
 certifi==2025.7.14
 charset-normalizer==3.4.2
-geoalchemy2==0.18.0
+geoalchemy2===0.17.1; python_version == 3.9
+geoalchemy2==0.18.0; python_version >= 3.10
 google-api-core[grpc]==2.25.1
 google-auth==2.40.3
 google-cloud-bigquery==3.35.1; python_version >= '3.9'