Add tags for ddtrace and lambda version (DataDog#87)

* Add tags for ddtrace and lambda version

* fixed linting

* removed space

* formatting

Author: meghna-dd

datadog_lambda/tracing.py

@@ -8,15 +8,16 @@
 
 from aws_xray_sdk.core import xray_recorder
 from aws_xray_sdk.core.lambda_launcher import LambdaContext
-
 from datadog_lambda.constants import (
     SamplingPriority,
     TraceHeader,
     XraySubsegment,
     TraceContextSource,
 )
 from ddtrace import tracer, patch
+from ddtrace import __version__ as ddtrace_version
 from ddtrace.propagation.http import HTTPPropagator
+from datadog_lambda import __version__ as datadog_lambda_version
 
 logger = logging.getLogger(__name__)
 
@@ -248,6 +249,8 @@ def create_function_execution_span(
             "function_version": function_version,
             "request_id": context.aws_request_id,
             "resource_names": context.function_name,
+            "datadog_lambda": datadog_lambda_version,
+            "dd_trace": ddtrace_version,
         }
     source = trace_context["source"]
     if source == TraceContextSource.XRAY and merge_xray_traces: