Bump wagtail from 6.1.3 to 6.3

Bumps [wagtail](https://github.com/wagtail/wagtail) from 6.1.3 to 6.3.
- [Release notes](https://github.com/wagtail/wagtail/releases)
- [Changelog](https://github.com/wagtail/wagtail/blob/main/CHANGELOG.txt)
- [Commits](wagtail/wagtail@v6.1.3...v6.3)

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

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

requirements.txt

@@ -154,7 +154,7 @@ uritools==4.0.3
 urllib3==2.2.3
 vine==5.1.0
 virtualenv==20.26.5
-wagtail==6.1.3
+wagtail==6.3
 wcwidth==0.2.13
 webencodings==0.5.1
 Willow==1.8.0