Rebuild for CUDA 12 w/arch + python312

[regro-cf-autotick-bot]

This PR has been triggered in an effort to update cuda120.

Besides that, the python312 migration from #3 has also been cherry-picked into this PR. Note that we have tried compiling for TORCH_CUDA_ARCH_LIST=8.0;8.6;8.9;9.0+PTX, but decided to stick with TORCH_CUDA_ARCH_LIST=8.0+PTX only to keep builds under CI limit of 6 hours as mentioned at #1 (comment)

This PR will thus result in 10 matrix builds on Linux for:

• Python 3.8 to 3.12 (5 versions)
• CUDA 11.8 and 12.0 (2 versions)

Notes and instructions for merging this PR:

1. Please merge the PR only after the tests have passed.
2. Feel free to push to the bot's branch to update this PR if needed.

Please note that if you close this PR we presume that the feedstock has been rebuilt, so if you are going to perform the rebuild yourself don't close this PR until the your rebuild has been merged.

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Here are some more details about this specific migrator:

The transition to CUDA 12 SDK includes new packages for all CUDA libraries and
build tools. Notably, the cudatoolkit package no longer exists, and packages
should depend directly on the specific CUDA libraries (libcublas, libcusolver,
etc) as needed. For an in-depth overview of the changes and to report problems
see this issue.
Please feel free to raise any issues encountered there. Thank you! 🙏

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If this PR was opened in error or needs to be updated please add the bot-rerun label to this PR. The bot will close this PR and schedule another one. If you do not have permissions to add this label, you can use the phrase @conda-forge-admin, please rerun bot in a PR comment to have the conda-forge-admin add it for you.

_{This PR was created by the regro-cf-autotick-bot. The regro-cf-autotick-bot is a service to automatically track the dependency graph, migrate packages, and propose package version updates for conda-forge. Feel free to drop us a line if there are any issues! This PR was generated by https://github.com/regro/cf-scripts/actions/runs/8994039733 - please use this URL for debugging.}

Closes #3

[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.

[weiji14]

Ah, was wondering why there weren't any CUDA 12.0 builds in the initial feedstock. I've cherry-picked some of the commits from #1 into here, so we can test building on CUDA 11.8 and 12.0. If all the builds pass, we can close #1 and just merge #2.

[weiji14]

Nice, compiliation completed for TORCH_CUDA_ARCH_LIST=8.0+PTX in about 4 hours across all matrix builds. Gonna merge this in now!