AVRO-4308: [python] Fix interop build failure from setuptools package discovery (#3894)

The local Docker interop build failed with "Multiple top-level packages
discovered in a flat-layout: ['avro', 'userlogs']". The Hadoop tether
tests leave a userlogs/ directory next to the avro/ package, which breaks
setuptools automatic flat-layout package discovery.

Explicitly scope package discovery to avro* so stray directories such as
userlogs/ are ignored.

Author: iemejia

lang/py/pyproject.toml

@@ -56,6 +56,9 @@ zstandard = ["zstandard"]
 [tool.ruff]
 line-length = 150
 
+[tool.setuptools.packages.find]
+include = ["avro*"]
+
 [tool.setuptools.package-data]
 "avro" = [
   "HandshakeRequest.avsc", "HandshakeResponse.avsc", "LICENSE.txt",