Bump djangorestframework in /{{cookiecutter.project_slug}} (#763)

Bumps [djangorestframework](https://github.com/encode/django-rest-framework) from 3.14.0 to 3.15.1.
- [Release notes](https://github.com/encode/django-rest-framework/releases)
- [Commits](encode/django-rest-framework@3.14.0...3.15.1)

---
updated-dependencies:
- dependency-name: djangorestframework
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

{{cookiecutter.project_slug}}/Pipfile

@@ -17,7 +17,7 @@ django-storages = "~=1.14"
 psycopg2 = "<=2.9"
 waitress = "~=2.1.2"
 whitenoise = "~=6.7.0"
-djangorestframework = "~=3.14.0"
+djangorestframework = "~=3.15.1"
 django-bootstrap4 = "~=22.1"
 django-allauth = "~=0.54.0"
 django-extensions = "~=3.2.3"