Remove onnx<1.14 from requirements.txt (#447)

* remove onnx<1.14 from requirements.txt

* downgrade protobuf

* move protobuf req to requirements-dev.txt

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Co-authored-by: Sayan Shaw <sayanshaw@microsoft.com>
Co-authored-by: Wenbing Li <10278425+wenbingl@users.noreply.github.com>

requirements-dev.txt

@@ -5,3 +5,4 @@ pytest
 onnxruntime      >=1.10.0
 transformers     >= 4.9.2,<=4.24.0
 tensorflow_text  >=2.5.0
+protobuf==3.20.*

requirements.txt

@@ -1,2 +1 @@
-# 1.14 hasn't be supported yet.
-onnx>=1.9.0,<1.14
+onnx>=1.9.0