Update semantic-conventions-java version to v1.30.0-rc.1

Author: opentelemetrybot

content/en/docs/languages/java/_index.md

@@ -9,7 +9,7 @@ cascade:
     instrumentation: 2.12.0
     otel: 1.46.0
     contrib: 1.43.0
-    semconv: 1.29.0
+    semconv: 1.30.0-rc.1
 weight: 18
 ---