feat: validate district number in district URL pattern

validate the URL pattern to only allow 1-12 for district number

Author: lalver1

pems/districts/urls.py

@@ -2,13 +2,13 @@
 URLConf for the districts app.
 """
 
-from django.urls import path
+from django.urls import path, re_path
 
 from pems.districts import views
 
 app_name = "districts"
 urlpatterns = [
     # /districts
     path("", views.IndexView.as_view(), name="index"),
-    path("<int:district_number>", views.DistrictView.as_view(), name="district"),
+    re_path(r"^(?P<district_number>([1-9]|1[0-2]))$", views.DistrictView.as_view(), name="district"),
 ]