[manual] Add Humbug notification bot user

The production database will need to have this user created before
this commit is pushed

(imported from commit cc8356d8afa0f0747486b7b4c82337c60499d3fd)

zephyr/management/commands/populate_db.py

@@ -192,6 +192,7 @@ class Command(BaseCommand):
             hardcoded_humbug_users_nosubs = [
                 ("Humbug New User Bot", "humbug+signups@humbughq.com"),
                 ("Humbug Error Bot", "humbug+errors@humbughq.com"),
+                ("Humbug Notification Bot", "humbug+notifications@humbughq.com"),
                 ]
             create_users(realms, hardcoded_humbug_users_nosubs)