chore(deps): Bump pip in /examples/knative/python/kn-py-vro

Bumps [pip](https://github.com/pypa/pip) from 21.1 to 23.3.
- [Changelog](https://github.com/pypa/pip/blob/main/NEWS.rst)
- [Commits](pypa/pip@21.1...23.3)

---
updated-dependencies:
- dependency-name: pip
  dependency-type: direct:production
...

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

examples/knative/python/kn-py-vro/requirements.txt

@@ -10,7 +10,7 @@ Flask==2.3.2
   Jinja2==3.1.2
     MarkupSafe==2.1.1
   Werkzeug==3.0.1
-pip==21.1
+pip==23.3
 python-dateutil==2.8.2
   six==1.16.0
 regex==2021.11.10