Update testcontainers-version to v1.21.0

Author: xdev-renovate

chartjs-java-model/pom.xml

@@ -50,7 +50,7 @@
 
 		<slf4j-version>2.0.17</slf4j-version>
 		<log4j-version>2.24.3</log4j-version>
-		<testcontainers-version>1.20.6</testcontainers-version>
+		<testcontainers-version>1.21.0</testcontainers-version>
 
 		<!-- by default run no tests as Docker is required -->
 		<skipTests>true</skipTests>