Registry: make tomllib fallback version-aware

[shahar1]

Use explicit Python-version check for tomllib fallback in registry extract scripts.

Why:

• Make fallback path deterministic by Python version instead of exception-driven import flow.
• Keep registry scripts aligned and easier to read.

Changes:

1. dev/registry/extract_metadata.py

• Add sys import.
• Switch tomllib/tomli import to version-aware if/else.

2. dev/registry/extract_versions.py

• Switch tomllib/tomli import to version-aware if/else.

This PR was split from #66250 to keep scope focused.

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Was generative AI tooling used to co-author this PR?

• Yes — GitHub Copilot (GPT-5.3-Codex)

Generated-by: GitHub Copilot (GPT-5.3-Codex) following the guidelines

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Drafted-by: GitHub Copilot (GPT-5.3-Codex) (no human review before posting)

[Copilot]

Pull request overview

This PR makes the tomllib vs tomli import path in the registry extraction scripts deterministic by switching from exception-driven imports to an explicit Python version check (sys.version_info >= (3, 11)), improving readability and consistency across the scripts.

Changes:

• Update extract_metadata.py to import sys and use a version-aware tomllib/tomli import.
• Update extract_versions.py to use the same version-aware tomllib/tomli import pattern.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
dev/registry/extract_metadata.py	Adds sys and switches TOML parsing import logic to a Python-version-based conditional.
dev/registry/extract_versions.py	Switches TOML parsing import logic to a Python-version-based conditional.

[github-actions]

Backport failed to create: v3-2-test. View the failure log Run details

Note: As of Merging PRs targeted for Airflow 3.X
the committer who merges the PR is responsible for backporting the PRs that are bug fixes (generally speaking) to the maintenance branches.

In matter of doubt please ask in #release-management Slack channel.

Status	Branch	Result
❌	v3-2-test

You can attempt to backport this manually by running:

cherry_picker 5b30aca v3-2-test

This should apply the commit to the v3-2-test branch and leave the commit in conflict state marking
the files that need manual conflict resolution.

After you have resolved the conflicts, you can continue the backport process by running:

cherry_picker --continue

If you don't have cherry-picker installed, see the installation guide.