Update apidiff baseline to released version 1.39.0 (#403)

Co-authored-by: otelbot <197425009+otelbot@users.noreply.github.com>

Author: otelbot[bot]

docs/apidiffs/1.39.0_vs_1.38.0/opentelemetry-semconv.txt

@@ -0,0 +1,4 @@
+Comparing source compatibility of opentelemetry-semconv-1.39.0.jar against opentelemetry-semconv-1.38.0.jar
+***  MODIFIED CLASS: PUBLIC FINAL io.opentelemetry.semconv.SchemaUrls  (not serializable)
+	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
+	+++  NEW FIELD: PUBLIC(+) STATIC(+) FINAL(+) java.lang.String V1_39_0

docs/apidiffs/current_vs_latest/opentelemetry-semconv.txt

@@ -1,4 +1,2 @@
-Comparing source compatibility of opentelemetry-semconv-1.39.0-SNAPSHOT.jar against opentelemetry-semconv-1.38.0.jar
-***  MODIFIED CLASS: PUBLIC FINAL io.opentelemetry.semconv.SchemaUrls  (not serializable)
-	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
-	+++  NEW FIELD: PUBLIC(+) STATIC(+) FINAL(+) java.lang.String V1_39_0
+Comparing source compatibility of opentelemetry-semconv-1.39.0-SNAPSHOT.jar against opentelemetry-semconv-1.39.0.jar
+No changes.