Update dependency io.vertx:vertx-rx-java2 to v4.5.15

Author: renovate[bot]

src/main/resources/build.gradle.kts

@@ -14,7 +14,7 @@ repositories {
 
 dependencies {
     implementation("io.vertx:vertx-core:4.5.12")
-    implementation("io.vertx:vertx-rx-java2:4.5.11")
+    implementation("io.vertx:vertx-rx-java2:4.5.15")
     implementation("io.vertx:vertx-web-client:4.5.13")
 
     implementation("io.vertx:vertx-lang-kotlin:4.5.13")