Bump black from 25.12.0 to 26.3.1

[dependabot]

Bumps black from 25.12.0 to 26.3.1.

Release notes

Sourced from black's releases.

26.3.1

Stable style

• Prevent Jupyter notebook magic masking collisions from corrupting cells by using exact-length placeholders for short magics and aborting if a placeholder can no longer be unmasked safely (#5038)

Configuration

• Always hash cache filename components derived from --python-cell-magics so custom magic names cannot affect cache paths (#5038)

Blackd

• Disable browser-originated requests by default, add configurable origin allowlisting and request body limits, and bound executor submissions to improve backpressure (#5039)

26.3.0

Stable style

• Don't double-decode input, causing non-UTF-8 files to be corrupted (#4964)
• Fix crash on standalone comment in lambda default arguments (#4993)
• Preserve parentheses when # type: ignore comments would be merged with other comments on the same line, preventing AST equivalence failures (#4888)

Preview style

• Fix bug where if guards in case blocks were incorrectly split when the pattern had a trailing comma (#4884)
• Fix string_processing crashing on unassigned long string literals with trailing commas (one-item tuples) (#4929)
• Simplify implementation of the power operator "hugging" logic (#4918)

Packaging

• Fix shutdown errors in PyInstaller builds on macOS by disabling multiprocessing in frozen environments (#4930)

Performance

• Introduce winloop for windows as an alternative to uvloop (#4996)
• Remove deprecated function uvloop.install() in favor of uvloop.new_event_loop() (#4996)
• Rename maybe_install_uvloop function to maybe_use_uvloop to simplify loop installation and creation of either a uvloop/winloop evenloop or default eventloop (#4996)

Output

... (truncated)

Changelog

Sourced from black's changelog.

Version 26.3.1

Stable style

• Prevent Jupyter notebook magic masking collisions from corrupting cells by using exact-length placeholders for short magics and aborting if a placeholder can no longer be unmasked safely (#5038)

Configuration

• Always hash cache filename components derived from --python-cell-magics so custom magic names cannot affect cache paths (#5038)

Blackd

• Disable browser-originated requests by default, add configurable origin allowlisting and request body limits, and bound executor submissions to improve backpressure (#5039)

Version 26.3.0

Stable style

• Don't double-decode input, causing non-UTF-8 files to be corrupted (#4964)
• Fix crash on standalone comment in lambda default arguments (#4993)
• Preserve parentheses when # type: ignore comments would be merged with other comments on the same line, preventing AST equivalence failures (#4888)

Preview style

• Fix bug where if guards in case blocks were incorrectly split when the pattern had a trailing comma (#4884)
• Fix string_processing crashing on unassigned long string literals with trailing commas (one-item tuples) (#4929)
• Simplify implementation of the power operator "hugging" logic (#4918)

Packaging

• Fix shutdown errors in PyInstaller builds on macOS by disabling multiprocessing in frozen environments (#4930)

Performance

• Introduce winloop for windows as an alternative to uvloop (#4996)
• Remove deprecated function uvloop.install() in favor of uvloop.new_event_loop() (#4996)
• Rename maybe_install_uvloop function to maybe_use_uvloop to simplify loop installation and creation of either a uvloop/winloop eventloop or default eventloop (#4996)

... (truncated)

Commits

• c6755bb Prepare release 26.3.1 (#5046)
• 69973fd Harden blackd browser-facing request handling (#5039)
• 4937fe6 Fix some shenanigans with the cache file and IPython (#5038)
• 2e641d1 docs: remove outdated Black Playground references (#5044)
• c014b22 Remove unused internal code (#5041)
• 0dae20b Add new changelog (#5036)
• c5c1cbd Minor release patches (#5035)
• 7e5a828 docs: clarify relationship between Black style and PEP 8 (#5025)
• 69705de docs: add clearer pyproject configuration guidance (#5026)
• 35ea679 Prepare release 26.3.0 (#5032)
• Additional commits viewable in compare view

Note
Automatic rebases have been disabled on this pull request as it has been open for over 30 days.

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PR Summary

Low Risk
Dev-dependency and lockfile-only change; affects local/CI formatting, not production runtime behavior.

Overview
Bumps the dev formatter black from 25.12.0 to 26.3.1 in pyproject.toml and refreshes poetry.lock.

The lockfile also picks up black’s updated transitive pins: pytokens 0.3.0 → 0.4.1 (constrained to <0.5.0), pathspec >=0.9.0 → >=1.0.0, and optional winloop on Windows for the uvloop extra. No application or runtime dependency changes.

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[panther-windmill-bot]

@dependabot rebase

[panther-windmill-bot]

@dependabot rebase

[panther-windmill-bot]

@dependabot rebase