Update gunicorn requirement from <24,>=23 to >=25,<26 (#270)

* Update gunicorn requirement from <24,>=23 to >=23,<26

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...25.0.1)

---
updated-dependencies:
- dependency-name: gunicorn
  dependency-version: 25.0.1
  dependency-type: direct:production
...

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

* Increase requirement version lower bound

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Ed Morley <501702+edmorley@users.noreply.github.com>

Author: dependabot[bot]

requirements.txt

@@ -1,5 +1,5 @@
 django>=6.0,<6.1
-gunicorn>=23,<24
+gunicorn>=25,<26
 dj-database-url>=3,<4
 whitenoise>=6,<7