chore: remove Python < 3.9 support (#728)

[ozeranskii]

What was changed

Bumped the minimum supported Python version from 3.8 to 3.9

• In build.py, changed the feature from pyo3/abi3-py38 to pyo3/abi3-py39.
• Updated references in README.md, pyproject.toml, and various dependencies to indicate the base version is now Python 3.9 and higher.

Removed code tied to older logic for macOS and Python < 3.8

• Removed the fragment with multiprocessing.set_start_method("spawn", True) for Python versions below 3.8, since the minimum supported version is now 3.9.

Why?

Project officially transitions to supporting Python 3.9+, and the Rust binding build now uses the ABI for Python 3.9 instead of 3.8.

Checklist

1. Closes [Feature Request] Update Ruff target version to 3.9 #728

2. How was this tested:

3. Any docs updates needed?

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[cretz]

Thanks! Unsure if we want to update all dependencies (at least in this PR), though if we do, I think CI is breaking with newer type expectations.

@dandavison - thoughts?

[ozeranskii]

@cretz Hi! About updating dependencies, I didn't update them purposefully, I just did poetry lock --no-update as I think you did in this commit 7af48a7#diff-f53a023eedfa3fbf2925ec7dc76eecdc954ea94b7e47065393dbad519613dc89.

can you please tell me if we should fix mypy?

[cretz]

I just did poetry lock --no-update

Hrmm, ok. I don't think we need to do that as part of this PR since only the ruff setting is changing in the project file. Can probably revert the lock update.

Though I am unsure why that command would have changed the lock file the way it did. The lock file has updated dependencies so I wonder if a poetry update happened.

[ozeranskii]

I think you're right and it's better to rollback poetry.lock now.

[ozeranskii]

@cretz 708e74b done

[cretz]

Merged main back into your branch and running CI again, will merge when it passes

[ozeranskii]

Merged main back into your branch and running CI again, will merge when it passes

main seems to have broken linter

[cretz]

Yes, it looks like the auto merge made test_replayer.py invalid format. If you would be willing to pull this branch and poe format and commit/push, that should fix it.

[ozeranskii]

Yes, it looks like the auto merge made test_replayer.py invalid format. If you would be willing to pull this branch and poe format and commit/push, that should fix it.

Fixed. Running CI again, please.

[cretz]

The failure in CI is due to an unrelated thing, but we may have to fix it before merging this. When fixed, I'll merge in to this. Sorry for all the waiting.

[ozeranskii]

The failure in CI is due to an unrelated thing, but we may have to fix it before merging this. When fixed, I'll merge in to this. Sorry for all the waiting.

ok, no problem. Thank you

[ozeranskii]

@cretz Hi. Can you please tell me how things are going with this PR?

[cretz]

Looks like @dandavison just did some rebasing against main, re-running CI now...

[dandavison]

Thanks for this work @ozeranskii.