Build(deps): bump willow from 1.6.2 to 1.6.3

Bumps [willow](https://github.com/wagtail/Willow) from 1.6.2 to 1.6.3.
- [Release notes](https://github.com/wagtail/Willow/releases)
- [Changelog](https://github.com/wagtail/Willow/blob/main/docs/changelog.rst)
- [Commits](wagtail/Willow@v1.6.2...v1.6.3)

---
updated-dependencies:
- dependency-name: willow
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

requirements.txt

@@ -79,7 +79,7 @@ django-flatblocks==1.0.0
 django-storages==1.14.2
 
 djangorestframework==3.14.0
-Willow==1.6.2
+Willow==1.6.3
 text-unidecode==1.3  # for faker
 html5lib==1.1