Bump wagtail from 4.0.4 to 6.3

Bumps [wagtail](https://github.com/wagtail/wagtail) from 4.0.4 to 6.3.
- [Release notes](https://github.com/wagtail/wagtail/releases)
- [Changelog](https://github.com/wagtail/wagtail/blob/main/CHANGELOG.txt)
- [Commits](wagtail/wagtail@v4.0.4...v6.3)

---
updated-dependencies:
- dependency-name: wagtail
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

requirements.txt

@@ -98,7 +98,7 @@ django-contact-us==1.1.0
 entrypoints==0.4
 
 # wagtail requirements
-wagtail==4.0.4
+wagtail==6.3
 django-modelcluster>=6.0,<7.0
 django-permissionedforms>=0.1,<1.0
 django-taggit>=5.0.1,<7.0