Update whitenoise requirement from <4.0,>=3.3 to >=3.3,<6.0

Updates the requirements on [whitenoise](https://github.com/evansd/whitenoise) to permit the latest version.
- [Release notes](https://github.com/evansd/whitenoise/releases)
- [Changelog](https://github.com/evansd/whitenoise/blob/master/docs/changelog.rst)
- [Commits](evansd/whitenoise@v3.3.0...v5.1.0)

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

requirements.txt

@@ -2,6 +2,6 @@ django>=2.2.10,<2.3
 django-extensions>=2.1,<2.2
 django-filter>=2.0,<2.1
 django-cors-headers>=2.4,<2.5
-whitenoise>=3.3,<4.0
+whitenoise>=3.3,<6.0
 psycopg2==2.8.4
 gunicorn==20.0.4