Require "sender" argument to send_sms method

In response to [^1].

[^1]: https://github.com/alphagov/notifications-api/pull/3493#discussion_r836616675

app/clients/sms/__init__.py

@@ -38,7 +38,7 @@ class SmsClient(Client):
             self.statsd_client.incr(f"clients.{self.name}.error")
             self.current_app.logger.warning(log_message)
 
-    def send_sms(self, to, content, reference, international, sender=None):
+    def send_sms(self, to, content, reference, international, sender):
         start_time = monotonic()
         sender = self.from_number if sender is None else sender
 

tests/app/clients/test_sms.py

@@ -24,6 +24,7 @@ def test_send_sms(fake_client, mocker):
         content='content',
         reference='reference',
         international=False,
+        sender=None,
     )
 
     mock_send.assert_called_with(
@@ -42,6 +43,7 @@ def test_send_sms_error(fake_client, mocker):
             content='content',
             reference='reference',
             international=False,
+            sender=None,
         )