Cuando implemento una aplicación python3 con Google App Engine Flex, aparece el siguiente error:

 File "<frozen importlib._bootstrap>", line 994, in _gcd_import File "<frozen importlib._bootstrap>", line 971, in _find_and_load File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked File "<frozen importlib._bootstrap>", line 665, in _load_unlocked File "<frozen importlib._bootstrap_external>", line 678, in exec_module File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed File "/home/vmagent/app/run.py", line 8, in <module> app = create_app(os.getenv('FLASK_CONFIG') or 'default') File "/home/vmagent/app/application/__init__.py", line 43, in create_app from .main import main as main_blueprint File "/home/vmagent/app/application/main/__init__.py", line 5, in <module> from . import cron_jobs, views File "/home/vmagent/app/application/main/cron_jobs.py", line 4, in <module> from google.cloud import datastore File "/env/lib/python3.6/site-packages/google/cloud/datastore/__init__.py", line 60, in <module> from google.cloud.datastore.batch import Batch File "/env/lib/python3.6/site-packages/google/cloud/datastore/batch.py", line 24, in <module> from google.cloud.datastore import helpers File "/env/lib/python3.6/site-packages/google/cloud/datastore/helpers.py", line 29, in <module> from google.cloud.datastore_v1.proto import datastore_pb2 File "/env/lib/python3.6/site-packages/google/cloud/datastore_v1/__init__.py", line 18, in <module> from google.cloud.datastore_v1.gapic import datastore_client File "/env/lib/python3.6/site-packages/google/cloud/datastore_v1/gapic/datastore_client.py", line 18, in <module> import google.api_core.gapic_v1.client_info File "/env/lib/python3.6/site-packages/google/api_core/gapic_v1/__init__.py", line 26, in <module> from google.api_core.gapic_v1 import method_async # noqa: F401 File "/env/lib/python3.6/site-packages/google/api_core/gapic_v1/method_async.py", line 20, in <module> from google.api_core import general_helpers, grpc_helpers_async File "/env/lib/python3.6/site-packages/google/api_core/grpc_helpers_async.py", line 145, in <module> class _WrappedStreamUnaryCall(_WrappedUnaryResponseMixin, _WrappedStreamRequestMixin, aio.StreamUnaryCall): AttributeError: module 'grpc.experimental.aio' has no attribute 'StreamUnaryCall'

Mi archivo requirements.txt incluye lo siguiente:

 google-cloud-datastore==1.12.0 grpcio==1.27.2

La razón por la que estoy usando la versión 1.27.2 de grpcio en lugar de la 1.29.0 más reciente es por la información que se muestra aquí .

¿Alguien puede ayudar?