[deps] Update pillow requirement in the pip group

Updates the requirements on [pillow](https://github.com/python-pillow/Pillow) to permit the latest version.

Updates `pillow` to 10.4.0
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/main/CHANGES.rst)
- [Commits](python-pillow/Pillow@9.5.0...10.4.0)

---
updated-dependencies:
- dependency-name: pillow
  dependency-type: direct:production
  dependency-group: pip
...

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

requirements.txt

@@ -2,6 +2,6 @@
 django>=3.2.18,!=4.0.*,<4.3
 channels~=3.0.4
 django-leaflet~=0.29.0
-Pillow~=9.5.0
+Pillow~=10.4.0
 geopy~=2.3.0
 openwisp-utils @ https://github.com/openwisp/openwisp-utils/tarball/master