Update drf-spectacular[sidecar] requirement

Updates the requirements on [drf-spectacular[sidecar]](https://github.com/tfranzel/drf-spectacular) to permit the latest version.
- [Release notes](https://github.com/tfranzel/drf-spectacular/releases)
- [Changelog](https://github.com/tfranzel/drf-spectacular/blob/master/CHANGELOG.rst)
- [Commits](tfranzel/drf-spectacular@0.26.2...0.28.0)

---
updated-dependencies:
- dependency-name: drf-spectacular[sidecar]
  dependency-type: direct:production
...

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

requirements/base.txt

@@ -7,7 +7,7 @@ django-userforeignkey>=0.3,<0.6
 drf-multitokenauth>=2.0.0,<2.2.0
 django-rest-registration>=0.8.3,<0.10
 django-rest-passwordreset>=1.1,<1.6
-drf-spectacular[sidecar]>=0.26.2,<0.28
+drf-spectacular[sidecar]>=0.26.2,<0.29
 django-environ>=0.10.0,<0.12
 django-gravatar2>=1.4.4,<1.5
 sentry-sdk>=2.9.0,<2.19