Update dependency org.testcontainers:testcontainers to v1.21.0

Author: xdev-renovate

testcontainers-advanced-imagebuilder/pom.xml

@@ -91,7 +91,7 @@
 		<dependency>
 			<groupId>org.testcontainers</groupId>
 			<artifactId>testcontainers</artifactId>
-			<version>1.20.4</version>
+			<version>1.21.0</version>
 		</dependency>
 		<!-- Testcontainers is using outdated v1 -->
 		<dependency>