clients: cbc_proxy handles lambda invoke response

Signed-off-by: Toby Lorne <toby.lornewelch-richards@digital.cabinet-office.gov.uk>

tests/app/clients/test_cbc_proxy.py

@@ -29,6 +29,7 @@ def test_cbc_proxy_ld_client_has_correct_keys(cbc_proxy):
     assert secret == 'cbc-proxy-aws-secret-access-key'
 
 
+
 def test_cbc_proxy_create_and_send_invokes_function(mocker, cbc_proxy):
     identifier = 'my-identifier'
     headline = 'my-headline'
@@ -40,6 +41,10 @@ def test_cbc_proxy_create_and_send_invokes_function(mocker, cbc_proxy):
         create=True,
     )
 
+    ld_client_mock.invoke.return_value = {
+        'StatusCode': 200,
+    }
+
     cbc_proxy.create_and_send_broadcast(
         identifier=identifier,
         headline=headline,