Add post-link script to install faiss-cpu via pip

[dlqqq]

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

Context

• This PR is being made to bring Python 3.12 support to Jupyter AI when installed via Conda Forge.
• Only faiss-cpu==1.8.0 has distributions that support Python 3.12 environments. However, this is not available on Conda Forge yet: faiss v1.8.0 faiss-split-feedstock#75.
  • Even though installing packages via pip in a post-link script is not good practice, this is the only way to ensure Python 3.12 support for all Jupyter AI users.
• faiss-cpu==1.8.0.post1 is also missing distributions for macOS: Jupyter AI installation failing on x86 macOS jupyterlab/jupyter-ai#858
• Hence, I'm installing faiss-cpu via pip install "faiss-cpu<=1.8.0".

[conda-forge-webservices]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.