protobuf 4.21 breaks onnx so freezing it as a workaround

see discussion here:
https://github.com/protocolbuffers/protobuf/issues/10051

Add FPGA Flow tutorial

Attempt to match upstream.

Changes to pre-commit YAML file

GPU training support for the cybersecurity MLP notebook

Signed-off-by: Alessandro Pappalardo <volcacius@users.noreply.github.com>

Signed-off-by: Alessandro Pappalardo <volcacius@users.noreply.github.com>

Make Pool_Batch more flexible

Streaming Concat op support