Bump drf-spectacular[sidecar] from 0.26.3 to 0.26.4

Bumps [drf-spectacular[sidecar]](https://github.com/tfranzel/drf-spectacular) from 0.26.3 to 0.26.4.
- [Release notes](https://github.com/tfranzel/drf-spectacular/releases)
- [Changelog](https://github.com/tfranzel/drf-spectacular/blob/master/CHANGELOG.rst)
- [Commits](tfranzel/drf-spectacular@0.26.3...0.26.4)

---
updated-dependencies:
- dependency-name: drf-spectacular[sidecar]
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

requirements.txt

@@ -22,7 +22,7 @@ django_compressor~=4.4
 django_extensions~=3.2
 django-storages~=1.13
 django-environ==0.10.0
-drf-spectacular[sidecar]==0.26.3
+drf-spectacular[sidecar]==0.26.4
 easy-thumbnails==2.8.5
 fontawesomefree~=6.4.0
 icalendar==5.0.7