Update django requirement from <3 to <6 in /echo-service

Updates the requirements on [django](https://github.com/django/django) to permit the latest version.
- [Commits](django/django@1.0...5.0.4)

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

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

echo-service/requirements.txt

@@ -1,6 +1,6 @@
 certifi==2022.12.7
 chardet==3.0.4
-Django<3
+Django<6
 djangorestframework<4
 drf-haystack<1.9
 idna==2.8