Update mypy requirement from <1.15,>=1.12 to >=1.12,<1.16 (#729)

Updates the requirements on [mypy](https://github.com/python/mypy) to permit the latest version.
- [Changelog](https://github.com/python/mypy/blob/master/CHANGELOG.md)
- [Commits](python/mypy@v1.12.0...v1.15.0)

---
updated-dependencies:
- dependency-name: mypy
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

setup.py

@@ -28,7 +28,7 @@ def find_stub_files(name: str) -> list[str]:
 
 # Keep compatible-mypy major.minor version pinned to what latest django-stubs release uses.
 extras_require = {
-    "compatible-mypy": ["mypy>=1.12,<1.15", "django-stubs[compatible-mypy]"],
+    "compatible-mypy": ["mypy>=1.12,<1.16", "django-stubs[compatible-mypy]"],
     "coreapi": ["coreapi>=2.0.0"],
     "markdown": ["types-Markdown>=0.1.5"],
 }