source is not default anymore

Author: sentrivana

tests/tracing/test_span_streaming.py

@@ -1540,7 +1540,6 @@ def test_transport_format(sentry_init, capture_envelopes):
                 "start_timestamp": mock.ANY,
                 "end_timestamp": mock.ANY,
                 "attributes": {
-                    "sentry.span.source": {"value": "custom", "type": "string"},
                     "thread.id": {"value": mock.ANY, "type": "string"},
                     "thread.name": {"value": "MainThread", "type": "string"},
                     "sentry.segment.id": {"value": mock.ANY, "type": "string"},