Update whitenoise requirement from ~=6.8.0 to >=6.8,<6.12

Updates the requirements on [whitenoise](https://github.com/evansd/whitenoise) to permit the latest version.
- [Changelog](https://github.com/evansd/whitenoise/blob/main/docs/changelog.rst)
- [Commits](evansd/whitenoise@6.8.0...6.11.0)

---
updated-dependencies:
- dependency-name: whitenoise
  dependency-version: 6.11.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

pyproject.toml

@@ -58,7 +58,7 @@ dependencies = [
   "setuptools",
   "urlman~=2.0.1",
   "vobject~=0.9.0",
-  "whitenoise~=6.8.0",
+  "whitenoise>=6.8,<6.12",
   "zxcvbn~=4.4.0",
   "pretalx_pages @ git+https://github.com/hongquan/eventyay-talk-pages.git@2956f13",
   "pretalx_venueless @ git+https://github.com/fossasia/eventyay-talk-video.git@main",