Bump mypy from 1.14.1 to 1.15.0 in /server

Bumps [mypy](https://github.com/python/mypy) from 1.14.1 to 1.15.0.
- [Changelog](https://github.com/python/mypy/blob/master/CHANGELOG.md)
- [Commits](python/mypy@v1.14.1...v1.15.0)

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

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

server/mypy-requirements.txt

@@ -1,4 +1,4 @@
-mypy==1.14.1
+mypy==1.15.0
 mypy-extensions==1.0
 types-Flask==1.1.6
 types-requests==2.32.0.20241016