created urls.py for calendar app and added calendar url to url paths

widget_princessgabi/widget_calendar/urls.py

+from django.urls import path
+
+from . import views
+
+urlpatterns = [
+    path('', views.index, name='calendar'),
+]
\ No newline at end of file

widget_princessgabi/widget_princessgabi/urls.py

@@ -14,8 +14,9 @@ Including another URLconf
     2. Add a URL to urlpatterns:  path('blog/', include('blog.urls'))
 """
 from django.contrib import admin
-from django.urls import path
+from django.urls import include, path
 
 urlpatterns = [
+    path('calendar/', include('widget_calendar.urls')),
     path('admin/', admin.site.urls),
 ]