Bump pip from 25.3 to 26.0.1 (#508)

* Bump pip from 25.3 to 26.0.1

Bumps [pip](https://github.com/pypa/pip) from 25.3 to 26.0.1.
- [Changelog](https://github.com/pypa/pip/blob/main/NEWS.rst)
- [Commits](pypa/pip@25.3...26.0.1)

---
updated-dependencies:
- dependency-name: pip
  dependency-version: 26.0.1
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

* Add changelog entry

* Update test assertion

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Ed Morley <501702+edmorley@users.noreply.github.com>

Author: dependabot[bot]

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- Updated pip from 25.3 to 26.0.1. ([#508](https://github.com/heroku/buildpacks-python/pull/508))
+
 ## [5.1.0] - 2026-02-26
 
 ### Changed

requirements/pip.txt

@@ -1 +1 @@
-pip==25.3
+pip==26.0.1

tests/pip_test.rs

@@ -274,7 +274,7 @@ fn pip_install_error() {
                 [Installing dependencies using pip]
                 Creating virtual environment
                 Running 'pip install -r requirements.txt'
-                ERROR: Invalid requirement: 'an-invalid-requirement!': Expected end or semicolon (after name and no valid version specifier)
+                ERROR: Invalid requirement: 'an-invalid-requirement!': Expected semicolon (after name with no version specifier) or end
                     an-invalid-requirement!
                                           ^ (from line 1 of requirements.txt)