Bump urllib3 from 1.26.2 to 1.26.3 in /py (#9311)

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.26.2 to 1.26.3.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/main/CHANGES.rst)
- [Commits](urllib3/urllib3@1.26.2...1.26.3)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: David Burns <david.burns@theautomatedtester.co.uk>

py/requirements.txt

@@ -20,5 +20,5 @@ sortedcontainers
 sniffio
 trio==0.17.0
 trio_websocket==0.9.0
-urllib3==1.26.2
+urllib3==1.26.3
 zipp