[Python Relase] Add xds-protos to release verification script (#34281)

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tools/release/verify_python_release.py

@@ -44,6 +44,7 @@ _DEFAULT_PACKAGES = [
     "grpcio-testing",
     "grpcio-admin",
     "grpcio-csds",
+    "xds-protos",
 ]
 
 Artifact = collections.namedtuple("Artifact", ("filename", "checksum"))