deps: update gunicorn requirement from <24,>=23.0 to >=23.0,<27

Updates the requirements on [gunicorn](https://github.com/benoitc/gunicorn) to permit the latest version.
- [Release notes](https://github.com/benoitc/gunicorn/releases)
- [Commits](benoitc/gunicorn@23.0.0...26.0.0)

---
updated-dependencies:
- dependency-name: gunicorn
  dependency-version: 26.0.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

pyproject.toml

@@ -39,7 +39,7 @@ dependencies = [
     # Pre-1.0 and major-version-risky deps are capped; floors are the versions
     # the suite is verified against.
     "fastapi>=0.116,<1.0",
-    "gunicorn>=23.0,<24",
+    "gunicorn>=23.0,<27",
     "orjson>=3.11,<4",
     "python-multipart>=0.0.19,<0.1",
     "pydantic>=2.13,<3",