build(deps): bump urllib3 from 1.24.2 to 1.26.18 in /py-legacy

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.24.2 to 1.26.18.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/main/CHANGES.rst)
- [Commits](urllib3/urllib3@1.24.2...1.26.18)

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

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

py-legacy/requirements.txt

@@ -23,5 +23,5 @@ requests-oauthlib==1.2.0
 requests==2.21.0
 rsa==4.0
 six==1.12.0
-urllib3==1.24.2
+urllib3==1.26.18
 websocket-client==0.55.0