Bump certifi from 2021.5.30 to 2021.10.8 in /perf-tests

Bumps [certifi](https://github.com/certifi/python-certifi) from 2021.5.30 to 2021.10.8.
- [Release notes](https://github.com/certifi/python-certifi/releases)
- [Commits](certifi/python-certifi@2021.05.30...2021.10.08)

---
updated-dependencies:
- dependency-name: certifi
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

perf-tests/requirements.txt

@@ -4,7 +4,7 @@ kubernetes==18.20.0
 pytest==4.4.1
 ipaddress==1.0.23 # >= 1.0.17
 cffi==1.14.6
-certifi==2021.5.30
+certifi==2021.10.8
 urllib3==1.26.7
 pytest-html==3.1.1
 pytest-repeat==0.9.1