get rid of none attributes

Author: sentrivana

sentry_sdk/integrations/opentelemetry/sampler.py

@@ -114,6 +114,8 @@ def should_sample(
 
         parent_span_context = trace.get_current_span(parent_context).get_span_context()
 
+        attributes = attributes or {}
+
         # No tracing enabled, thus no sampling
         if not has_tracing_enabled(client.options):
             return dropped_result(parent_span_context, attributes)