Update Apache Flink to 1.16.1 (1.16.0 artifacts are not available anymore)

Signed-off-by: Andriy Redko <andriy.redko@aiven.io>

Author: reta

.github/workflows/push_pr.yml

@@ -25,4 +25,4 @@ jobs:
   compile_and_test:
     uses: apache/flink-connector-shared-utils/.github/workflows/ci.yml@ci_utils
     with:
-      flink_version: 1.16.0
+      flink_version: 1.16.1

flink-connector-opensearch/src/main/java/org/apache/flink/connector/opensearch/sink/OpensearchAsyncSinkBuilder.java

@@ -31,7 +31,6 @@
 
 import static org.apache.flink.util.Preconditions.checkArgument;
 import static org.apache.flink.util.Preconditions.checkNotNull;
-import static org.apache.flink.util.Preconditions.checkState;
 
 /**
  * Builder to construct an Opensearch compatible {@link OpensearchAsyncSink}.

pom.xml

@@ -58,7 +58,7 @@ under the License.
 	</modules>
 
 	<properties>
-		<flink.version>1.16.0</flink.version>
+		<flink.version>1.16.1</flink.version>
 		<flink.shaded.version>15.0</flink.shaded.version>
 
 		<jackson-bom.version>2.13.4.20221013</jackson-bom.version>