Bump pip from 25.2 to 25.3

Bumps [pip](https://github.com/pypa/pip) from 25.2 to 25.3.
- [Changelog](https://github.com/pypa/pip/blob/main/NEWS.rst)
- [Commits](pypa/pip@25.2...25.3)

---
updated-dependencies:
- dependency-name: pip
  dependency-version: '25.3'
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements-initial.txt

@@ -1,5 +1,5 @@
 # requirements-initial.txt
 # From https://dist.plone.org/release/6.1.2/constraints.txt
-pip==25.2
+pip==25.3
 setuptools==80.9.0
 wheel==0.46.1