docs(pyproject): cloudpickle covers aggregate and window UDFs too

The dependency comment said "scalar UDF callables" but cloudpickle
has covered aggregate and window UDFs since 4b51402 / 89d119f.
Also note the OnceLock import cache landed in b5684bc so callers
pay one import per process, not one per UDF.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: timsaucer

pyproject.toml

@@ -45,9 +45,10 @@ classifiers = [
 ]
 dependencies = [
   # cloudpickle is invoked by the Rust-side PythonLogicalCodec /
-  # PythonPhysicalCodec via pyo3 to serialize Python scalar UDF
-  # callables into the proto wire format. Lazy-imported on the encode
-  # / decode hot paths, so users who never serialize a plan or
+  # PythonPhysicalCodec via pyo3 to serialize Python UDF callables —
+  # scalar, aggregate, and window — into the proto wire format.
+  # Lazy-imported on the encode / decode hot paths (and cached after
+  # the first import), so users who never serialize a plan or
   # expression incur no runtime cost beyond the install footprint.
   "cloudpickle>=2.0",
   "pyarrow>=16.0.0;python_version<'3.14'",