Update django-otp requirement from ==1.5.* to ==1.6.* (#4996)

Updates the requirements on [django-otp](https://github.com/django-otp/django-otp) to permit the latest version.
- [Changelog](https://github.com/django-otp/django-otp/blob/master/CHANGES.rst)
- [Commits](https://github.com/django-otp/django-otp/compare/v1.5.0...v1.6.0)

---
updated-dependencies:
- dependency-name: django-otp
  dependency-version: 1.6.0
  dependency-type: direct:production
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

pyproject.toml

@@ -49,7 +49,7 @@ dependencies = [
   "django-localflavor==4.0",
   "django-markup",
   "django-oauth-toolkit==2.3.*",
-  "django-otp==1.5.*",
+  "django-otp==1.6.*",
   "django-phonenumber-field==7.3.*",
   "django-redis==5.4.*",
   "django-scopes==2.0.*",