fix(deps): update dependency org.testcontainers:testcontainers to v2

Author: renovate[bot]

conversational-ai4j-demo/build.gradle

@@ -25,7 +25,7 @@ dependencies {
   testImplementation 'org.jsoup:jsoup:1.22.1'
 
   // Testcontainers for Docker integration tests
-  testImplementation 'org.testcontainers:testcontainers:1.21.4'
+  testImplementation 'org.testcontainers:testcontainers:2.0.3'
   testImplementation 'org.testcontainers:junit-jupiter:1.21.4'
 
   // Playwright for E2E testing