Bump wagtail from 3.0.3 to 4.2.2

Bumps [wagtail](https://github.com/wagtail/wagtail) from 3.0.3 to 4.2.2.
- [Release notes](https://github.com/wagtail/wagtail/releases)
- [Changelog](https://github.com/wagtail/wagtail/blob/main/CHANGELOG.txt)
- [Commits](wagtail/wagtail@v3.0.3...v4.2.2)

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

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

requirements.txt

@@ -78,7 +78,7 @@ django-storages==1.13
 Unidecode==1.3.2
 
 # wagtail requirements
-wagtail==3.0.3
+wagtail==4.2.2
 django-modelcluster>=6.0,<7.0
 django-permissionedforms>=0.1,<1.0
 django-taggit>=2.0,<4.0