Update flask requirement from ~=3.1.1 to ~=3.1.2

Updates the requirements on [flask](https://github.com/pallets/flask) to permit the latest version.
- [Release notes](https://github.com/pallets/flask/releases)
- [Changelog](https://github.com/pallets/flask/blob/main/CHANGES.rst)
- [Commits](pallets/flask@3.1.1...3.1.2)

---
updated-dependencies:
- dependency-name: flask
  dependency-version: 3.1.2
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements.txt

@@ -1,5 +1,5 @@
 ao3-api~=2.3.0
 feedgen~=1.0.0
-Flask~=3.1.1
+Flask~=3.1.2
 cachetools~=6.1.0
 MarkupSafe~=3.0.2