Try forcing grpcio-tools 1.64.1 for proto code gen.

Hoping this threads the needle between:
* protoc compatible with protobuf 5.27.5.
* Cython-generated code compatible with python 3.12.

pyproject.toml

@@ -1,12 +1,13 @@
 [build-system]
 requires = [
     "setuptools",
-    "farm-ng-package",
     "pybind11",
     "wheel",
-    # Ensure a Cython compatible with Python 3.12:
-    # https://github.com/cython/cython/issues/5285
-    "Cython>=0.29.37",
-
+    # farm-ng-package v0.1.4 locks protobuf/grpcio versions to those on Brain.
+    # However, grpcio 1.56.2 contains Cython-generated code that is incompatible
+    # with Python 3.12.
+    # If this works, then we should yank v0.1.4 or update.
+    "farm-ng-package==0.1.3",
+    "grpcio-tools==1.64.1",
 ]
 build-backend = "setuptools.build_meta"