Bump pip from 24.0 to 25.2 in /scripts/link_checker

Bumps [pip](https://github.com/pypa/pip) from 24.0 to 25.2.
- [Changelog](https://github.com/pypa/pip/blob/main/NEWS.rst)
- [Commits](pypa/pip@24.0...25.2)

---
updated-dependencies:
- dependency-name: pip
  dependency-version: '25.2'
  dependency-type: direct:production
...

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

Author: dependabot[bot]

scripts/link_checker/requirements.txt

@@ -1,4 +1,4 @@
-pip==24.0
+pip==25.2
 attrs==24.2.0
 idna==3.8
 multidict==6.0.5