Bump django-anymail[mailgun] from 9.2 to 11.1

Bumps [django-anymail[mailgun]](https://github.com/anymail/django-anymail) from 9.2 to 11.1.
- [Release notes](https://github.com/anymail/django-anymail/releases)
- [Changelog](https://github.com/anymail/django-anymail/blob/main/CHANGELOG.rst)
- [Commits](anymail/django-anymail@v9.2...v11.1)

---
updated-dependencies:
- dependency-name: django-anymail[mailgun]
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

requirements/base.txt

@@ -2,7 +2,7 @@
 django==3.2.25
 django-environ==0.11.2
 django-model-utils==4.5.1
-django-anymail[mailgun]==9.2
+django-anymail[mailgun]==11.1
 django-mail-templated==2.6.5
 django-allauth==0.55.2
 django-crispy-forms==1.14.0