style: spell out the pyo3 imports in the bundle example

Every other module in this crate names the pyo3 items it uses;
`extension.rs` arrived with a glob off the prelude. The crate's
rustfmt config asks for `imports_granularity = Module`, which would
have made the difference visible, but it is a nightly-only option and
CI checks formatting on stable, so nothing was going to flag it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: timsaucer

examples/datafusion-ffi-example/src/extension.rs

@@ -15,8 +15,8 @@
 // specific language governing permissions and limitations
 // under the License.
 
-use pyo3::prelude::*;
-use pyo3::types::PyDict;
+use pyo3::types::{PyAnyMethods, PyDict, PyDictMethods};
+use pyo3::{Bound, Py, PyAny, PyResult, Python, pyclass, pymethods};
 
 use crate::aggregate_udf::MySumUDF;
 use crate::scalar_udf::IsNullUDF;