fix(metrics): fix OpenTelemetry resource detector import path

Author: sinhasubham

packages/google-cloud-spanner/tests/_helpers.py

@@ -13,6 +13,9 @@
 
 try:
     from opentelemetry import trace
+    from opentelemetry.resourcedetector.gcp_resource_detector import (  # noqa: F401
+        GoogleCloudResourceDetector,
+    )
     from opentelemetry.sdk.trace import TracerProvider
     from opentelemetry.sdk.trace.export import SimpleSpanProcessor
     from opentelemetry.sdk.trace.export.in_memory_span_exporter import (