Bump urllib3 from 2.2.2 to 2.6.3 in /tools/wptrunner

Bumps [urllib3](https://github.com/urllib3/urllib3) from 2.2.2 to 2.6.3.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/main/CHANGES.rst)
- [Commits](urllib3/urllib3@2.2.2...2.6.3)

---
updated-dependencies:
- dependency-name: urllib3
  dependency-version: 2.6.3
  dependency-type: direct:production
...

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

Author: dependabot[bot]

tools/wptrunner/requirements.txt

@@ -9,5 +9,5 @@ pillow==11.3.0; python_version == '3.9'
 pillow==12.1.1; python_version >= '3.10'
 requests==2.32.3
 types-requests==2.32.0.20241016
-urllib3==2.2.2
+urllib3==2.6.3
 aioquic==1.2.0