Prepare to release v1.0.0-RC1 (stable) / v0.21.0 (unstable) (#186)

Author: punya

e2e-test-server/go.mod

@@ -4,7 +4,7 @@ go 1.16
 
 require (
 	cloud.google.com/go/pubsub v1.12.0
-	github.com/GoogleCloudPlatform/opentelemetry-operations-go/exporter/trace v0.0.0
+	github.com/GoogleCloudPlatform/opentelemetry-operations-go/exporter/trace v1.0.0-RC1
 	go.opentelemetry.io/otel v1.0.0-RC1
 	go.opentelemetry.io/otel/sdk v1.0.0-RC1
 	go.opentelemetry.io/otel/trace v1.0.0-RC1