Update dependency org.testcontainers:testcontainers to v1.21.4

Author: renovate[bot]

docker-network-client/pom.xml

@@ -17,7 +17,7 @@
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 		<java.version>1.8</java.version>
 		<rest-assured.version>4.5.1</rest-assured.version>
-		<testcontainers.version>1.21.3</testcontainers.version>
+		<testcontainers.version>1.21.4</testcontainers.version>
 	</properties>
 
 	<dependencies>