Update dependency org.testcontainers:testcontainers-bom to v1.21.3

Author: renovate[bot]

pom.xml

@@ -41,7 +41,7 @@
         <maven.compiler.target>17</maven.compiler.target>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <spring.boot.version>3.3.8</spring.boot.version>
-        <testcontainers.version>1.20.4</testcontainers.version>
+        <testcontainers.version>1.21.3</testcontainers.version>
         <tinylog.version>2.7.0</tinylog.version>
     </properties>