Bump certifi from 2020.4.5.1 to 2022.12.7 in /sample-apps/flask

Bumps [certifi](https://github.com/certifi/python-certifi) from 2020.4.5.1 to 2022.12.7.
- [Release notes](https://github.com/certifi/python-certifi/releases)
- [Commits](certifi/python-certifi@2020.04.05.1...2022.12.07)

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

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

Author: dependabot[bot]

sample-apps/flask/requirements.txt

@@ -1,5 +1,5 @@
 boto3
-certifi==2020.4.5.1
+certifi==2022.12.7
 chardet==3.0.4
 click==7.1.2
 Flask==1.1.2