Prevent ONNX RTE build if python package is not available

[al-rigazzi]

Description

When running smart build with Python 3.10, a user can build the ONNX RTE (and RedisAI backend) even if there is no compatible skl2onnx module available. smart build will correctly inform the user that the package does not exist, but the RedisAI backend will be built, and that can be confusing to users.

ONNX RTE and corresponding RedisAI backend should not be built in this scenario.

Justification

It is confusing (and can be the source of errors) to have a backend that cannot be used because of a lack of compatible modules. We should let the user know that we cannot support ONNX on Python 3.10, because or RedisAI limitations.

Implementation Strategy

At smart build time, a check should be added to prevent ONNX RTE and the corresponding RedisAI backend to be built.

Acceptance Criteria

• The RedisAI backend for ONNX is not built under Python 3.10