Update django-linear-migrations requirement

Updates the requirements on [django-linear-migrations](https://github.com/adamchainz/django-linear-migrations) to permit the latest version.
- [Changelog](https://github.com/adamchainz/django-linear-migrations/blob/main/CHANGELOG.rst)
- [Commits](adamchainz/django-linear-migrations@2.8.0...2.16.0)

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

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

requirements/test.txt

@@ -1,5 +1,5 @@
 -r base.txt
 
-django-linear-migrations>=2.8.0,<2.14
+django-linear-migrations>=2.8.0,<2.17
 pytest-django>=4.5.2,<4.10
 pytest-cov>=4.1.0,<5.1