Bump django-anymail from 13.0 to 13.1

Bumps [django-anymail](https://github.com/anymail/django-anymail) from 13.0 to 13.1.
- [Release notes](https://github.com/anymail/django-anymail/releases)
- [Changelog](https://github.com/anymail/django-anymail/blob/main/CHANGELOG.rst)
- [Commits](anymail/django-anymail@v13.0...v13.1)

---
updated-dependencies:
- dependency-name: django-anymail
  dependency-version: '13.1'
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

poetry.lock

@@ -33,7 +33,7 @@ numpy = "^2.2.4"
 pandas = "^2.2.3"
 whitenoise = "6.2.0" # currently should be hardcoded to 6.2.0
 django-admin-rangefilter = "^0.13.2"
-django-anymail = "^13.0"
+django-anymail = "^13.1"
 sentry-sdk = "^2.38.0"
 django-two-factor-auth = { extras = ["phonenumbers"], version = "^1.18.1" }
 django-simple-history = "^3.7.0"