Bump pipenv from 2026.5.1 to 2026.5.2 (#2080)

* Bump pipenv from 2026.5.1 to 2026.5.2

Bumps [pipenv](https://github.com/pypa/pipenv) from 2026.5.1 to 2026.5.2.
- [Release notes](https://github.com/pypa/pipenv/releases)
- [Changelog](https://github.com/pypa/pipenv/blob/main/CHANGELOG.md)
- [Commits](pypa/pipenv@v2026.5.1...v2026.5.2)

---
updated-dependencies:
- dependency-name: pipenv
  dependency-version: 2026.5.2
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

* Add changelog entry

---------

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

@@ -2,6 +2,7 @@
 
 ## [Unreleased]
 
+- Updated Pipenv from 2026.5.1 to 2026.5.2. ([#2080](https://github.com/heroku/heroku-buildpack-python/pull/2080))
 - Updated Poetry from 2.3.3 to 2.3.4. ([#2079](https://github.com/heroku/heroku-buildpack-python/pull/2079))
 - Updated uv from 0.11.3 to 0.11.6. ([#2078](https://github.com/heroku/heroku-buildpack-python/pull/2078))
 

requirements/pipenv.txt

@@ -1 +1 @@
-pipenv==2026.5.1
+pipenv==2026.5.2