Update datastore-v1-proto-client to 2.21.0 (#1010)

Author: scala-steward

build.sbt

@@ -27,7 +27,7 @@ val avroVersion = Option(sys.props("avro.version")).getOrElse("1.11.3")
 val bigqueryVersion = "v2-rev20240229-2.0.0"
 val bigtableVersion = "2.41.0"
 val catsVersion = "2.10.0"
-val datastoreVersion = "2.20.2"
+val datastoreVersion = "2.21.0"
 val guavaVersion = "33.2.1-jre"
 val hadoopVersion = "3.4.0"
 val jacksonVersion = "2.17.2"