Bump urllib3 from 1.26.7 to 1.26.8 in /perf-tests (#2344)

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.26.7 to 1.26.8.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/1.26.8/CHANGES.rst)
- [Commits](urllib3/urllib3@1.26.7...1.26.8)

---
updated-dependencies:
- dependency-name: urllib3
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

perf-tests/requirements.txt

@@ -5,7 +5,7 @@ pytest==4.4.1
 ipaddress==1.0.23 # >= 1.0.17
 cffi==1.15.0
 certifi==2021.10.8
-urllib3==1.26.7
+urllib3==1.26.8
 pytest-html==3.1.1
 pytest-repeat==0.9.1
 locust==2.5.1