Update pip requirement from <26 to <27 in the pip group

[dependabot]

Updates the requirements on pip to permit the latest version.
Updates pip to 26.2.1

Changelog

Sourced from pip's changelog.

26.2.1 (2026-08-04)

Bug Fixes

• Reallow keyring installed in a (non-activated) virtual environment to be be used via the import provider method while installing build dependencies. ([#14227](https://github.com/pypa/pip/issues/14227) <https://github.com/pypa/pip/issues/14227>_)

26.2 (2026-07-29)

Deprecations and Removals

• Newly published packages will no longer be immediately visible to pip if the index uses caching. To install a newly published package, use --refresh-package. ([#13680](https://github.com/pypa/pip/issues/13680) <https://github.com/pypa/pip/issues/13680>_)

• Drop support for detecting legacy, non-:pep:405, virtualenv (< 20) environments. ([#14062](https://github.com/pypa/pip/issues/14062) <https://github.com/pypa/pip/issues/14062>_)

• Constraints files, including PIP_CONSTRAINT, no longer affect isolated build environments. Use --build-constraint or the PIP_BUILD_CONSTRAINT environment variable to constrain build dependencies instead.

  The --use-feature=build-constraint flag is now always enabled and has no effect. ([#14094](https://github.com/pypa/pip/issues/14094) <https://github.com/pypa/pip/issues/14094>_)

Features

• Declare support for Python 3.15 ([#14208](https://github.com/pypa/pip/issues/14208) <https://github.com/pypa/pip/issues/14208>_)

• Support self-referential extras officially. pip has supported this by accident since version 21.2. ([#11296](https://github.com/pypa/pip/issues/11296) <https://github.com/pypa/pip/issues/11296>_)

• Add --only-deps flag to instruct pip to select only the dependencies of supplied packages. It cannot be used with --no-deps, -r, --group, or --requirements-from-script. ([#11440](https://github.com/pypa/pip/issues/11440) <https://github.com/pypa/pip/issues/11440>_)

• Cache simple responses in accordance to their Cache-Control header instead of always revalidating on every request. To refresh cached package index responses and ensure newly published packages are found, use --refresh-package <package>. ([#13680](https://github.com/pypa/pip/issues/13680) <https://github.com/pypa/pip/issues/13680>_)

• Add --no-require-hashes to disable automatic enablement of --require-hashes when encountering a requirement with hashes. ([#14169](https://github.com/pypa/pip/issues/14169) <https://github.com/pypa/pip/issues/14169>_)

• Honor --only-final when sourcing requirements with -r pylock.toml. ([#13950](https://github.com/pypa/pip/issues/13950) <https://github.com/pypa/pip/issues/13950>_)

• Add support for pylock.toml upload-time field, so --uploaded-prior-to works with -r pylock.toml. ([#14168](https://github.com/pypa/pip/issues/14168) <https://github.com/pypa/pip/issues/14168>_)

• Better error messages in case of conflicts with requirements from -r pylock.toml. ([#13963](https://github.com/pypa/pip/issues/13963) <https://github.com/pypa/pip/issues/13963>_)

• Add experimental support for isolating build subprocesses by creating standard virtual environments. This will fix most (if not all) subtle isolation issues that can lead to broken builds exclusive to pip. The feature can be enabled via --use-feature=venv-isolation and will be enabled by default in a future release.

  Note that the feature has limited compatibility with --use-feature=inprocess-build-deps.

... (truncated)

Commits

• 634a6ec Bump for release
• ae2eb4f Revert build dependency installer isolation for legacy build environment (#14...
• 6236392 Merge pull request #14213 from pypa/release/26.2
• da4b2cc Bump for development
• 4b6ae5c Bump for release
• 50b6d3c Update AUTHORS.txt
• dbddfbd Tweak news entries for pip 26.2 (#14212)
• 6576b75 Merge pull request #14165 from sbidoul/refactor-pylock-hanling-sbi
• 0090e00 Address a variety of typos detected in code review
• e12ddd9 Add support for --uploaded-prior-to with -r pylock.toml
• Additional commits viewable in compare view

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