Bump django-htmx from 1.19.0 to 1.21.0

Bumps [django-htmx](https://github.com/adamchainz/django-htmx) from 1.19.0 to 1.21.0.
- [Changelog](https://github.com/adamchainz/django-htmx/blob/main/docs/changelog.rst)
- [Commits](adamchainz/django-htmx@1.19.0...1.21.0)

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

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

pyproject.toml

@@ -14,7 +14,7 @@ dependencies = [
     "django-extensions==3.2.3",
     "django-hashid-field==3.4.1",
     "django-hijack==3.6.0",
-    "django-htmx==1.19.0",
+    "django-htmx==1.21.0",
     "django-ordered-model==3.7.4",
     "django-simple-history==3.7.0",
     "django-storages==1.14.4",