build(deps): bump pytest in /packages/bigframes/samples/polars

Bumps [pytest](https://github.com/pytest-dev/pytest) from 8.3.2 to 9.0.3.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/main/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@8.3.2...9.0.3)

---
updated-dependencies:
- dependency-name: pytest
  dependency-version: 9.0.3
  dependency-type: direct:production
...

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

Author: dependabot[bot]

packages/bigframes/samples/polars/requirements-test.txt

@@ -1,3 +1,3 @@
 # samples/snippets should be runnable with no "extras"
 google-cloud-testutils==1.4.0
-pytest==8.3.2
+pytest==9.0.3