Fix ci errors, specify minimum Django version

Author: vsalvino

cr_sendmail/backends.py

@@ -7,8 +7,8 @@
 from subprocess import Popen
 
 from django.conf import settings
-from django.core.mail.message import sanitize_address
 from django.core.mail.backends.base import BaseEmailBackend
+from django.core.mail.message import sanitize_address
 
 
 LOGGER = logging.getLogger("cr-sendmail-django")

pyproject.toml

@@ -17,7 +17,7 @@ classifiers = [
     "Framework :: Django",
 ]
 dependencies = [
-    "Django",
+    "Django>=1.3",
 ]
 description = "Django email backend which invokes system `sendmail` binary."
 dynamic = ["version"]

requirements-dev.txt

@@ -1,2 +1,3 @@
 build
 ruff
+mypy