Update django-anymail to 10.3 (cookiecutter#4919)

* Update django-anymail from 10.2 to 10.3

{{cookiecutter.project_slug}}/requirements/production.txt

@@ -24,21 +24,21 @@ django-storages[google]==1.14.2  # https://github.com/jschneier/django-storages
 django-storages[azure]==1.14.2  # https://github.com/jschneier/django-storages
 {%- endif %}
 {%- if cookiecutter.mail_service == 'Mailgun' %}
-django-anymail[mailgun]==10.2  # https://github.com/anymail/django-anymail
+django-anymail[mailgun]==10.3  # https://github.com/anymail/django-anymail
 {%- elif cookiecutter.mail_service == 'Amazon SES' %}
-django-anymail[amazon-ses]==10.2  # https://github.com/anymail/django-anymail
+django-anymail[amazon-ses]==10.3  # https://github.com/anymail/django-anymail
 {%- elif cookiecutter.mail_service == 'Mailjet' %}
-django-anymail[mailjet]==10.2  # https://github.com/anymail/django-anymail
+django-anymail[mailjet]==10.3  # https://github.com/anymail/django-anymail
 {%- elif cookiecutter.mail_service == 'Mandrill' %}
-django-anymail[mandrill]==10.2  # https://github.com/anymail/django-anymail
+django-anymail[mandrill]==10.3  # https://github.com/anymail/django-anymail
 {%- elif cookiecutter.mail_service == 'Postmark' %}
-django-anymail[postmark]==10.2  # https://github.com/anymail/django-anymail
+django-anymail[postmark]==10.3  # https://github.com/anymail/django-anymail
 {%- elif cookiecutter.mail_service == 'Sendgrid' %}
-django-anymail[sendgrid]==10.2  # https://github.com/anymail/django-anymail
+django-anymail[sendgrid]==10.3  # https://github.com/anymail/django-anymail
 {%- elif cookiecutter.mail_service == 'SendinBlue' %}
-django-anymail[sendinblue]==10.2  # https://github.com/anymail/django-anymail
+django-anymail[sendinblue]==10.3  # https://github.com/anymail/django-anymail
 {%- elif cookiecutter.mail_service == 'SparkPost' %}
-django-anymail[sparkpost]==10.2  # https://github.com/anymail/django-anymail
+django-anymail[sparkpost]==10.3  # https://github.com/anymail/django-anymail
 {%- elif cookiecutter.mail_service == 'Other SMTP' %}
-django-anymail==10.2  # https://github.com/anymail/django-anymail
+django-anymail==10.3  # https://github.com/anymail/django-anymail
 {%- endif %}