Bump flask from 0.12.2 to 2.2.5 in /leaderboard

Bumps [flask](https://github.com/pallets/flask) from 0.12.2 to 2.2.5.
- [Release notes](https://github.com/pallets/flask/releases)
- [Changelog](https://github.com/pallets/flask/blob/main/CHANGES.rst)
- [Commits](pallets/flask@0.12.2...2.2.5)

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

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

Author: dependabot[bot]

leaderboard/requirements.txt

@@ -1,7 +1,7 @@
 certifi==2022.12.7
 chardet==3.0.4
 click==6.7
-Flask==1.0
+Flask==2.2.5
 Flask-Cache==0.13.1
 Flask-FlatPages==0.6
 Flask-MySQL==1.4.0