Bump pipenv in /python/helpers in the pipenv group

Bumps the pipenv group in /python/helpers with 1 update: [pipenv](https://github.com/pypa/pipenv).


Updates `pipenv` from 2024.4.1 to 2026.0.3
- [Release notes](https://github.com/pypa/pipenv/releases)
- [Changelog](https://github.com/pypa/pipenv/blob/main/CHANGELOG.md)
- [Commits](pypa/pipenv@v2024.4.1...v2026.0.3)

---
updated-dependencies:
- dependency-name: pipenv
  dependency-version: 2026.0.3
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: pipenv
...

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

Author: dependabot[bot]

python/helpers/requirements.txt

@@ -2,7 +2,7 @@ pip==26.0
 pip-tools==7.5.2
 flake8==7.3.0
 hashin==1.0.5
-pipenv==2024.4.1
+pipenv==2026.0.3
 plette==2.1.0
 poetry==2.3.2
 # TODO: Replace 3p package `tomli` with 3.11's new stdlib `tomllib` once we drop support for Python 3.10.