in python 3.7.9:
pip install keras==2.3.1 tensorflow==1.15.2 h5py==2.10.0 protobuf==3.6.1
run keras_to_pb.py and remember output names then in a python 3.10.x shell run:
pip install tf2onnx
python -m tf2onnx.convert --input model.pb --inputs Tokenized_Sent_Input:0 --outputs Output_Predictions/Softmax:0 --output model_from_pb.onnx