openvino/workbench 2022.1 fails to convert model

[dnoliver]

To reproduce:

1. Start DL Workbench 2022.1
2. Import the "alexnet" model
3. Convert the model

Expected: Model should be converted to IR format
Actual: Model conversion fails.

In the server log, you can see an error message complaining about the protobuf version. It proposes 2 workarounds:

1. Downgrade the protobuf package to 3.20.x or lower.
2. Set PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION=python (but this will use pure-Python parsing and will be much slower).

I have tested both workarounds, and they work fine.