Bump django from 5.1.14 to 5.1.15 in /example

Bumps [django](https://github.com/django/django) from 5.1.14 to 5.1.15.
- [Commits](https://github.com/django/django/compare/5.1.14...5.1.15)

---
updated-dependencies:
- dependency-name: django
  dependency-version: 5.1.15
  dependency-type: direct:production
...

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

example/requirements.txt

@@ -2,7 +2,7 @@ asgiref==3.8.1
 beautifulsoup4==4.12.3
 certifi==2024.8.30
 charset-normalizer==3.4.0
-django==5.1.14
+django==5.1.15
 django-json-ld==0.0.5
 django-signposting==0.10.0
 httplink==0.2.0