Update to reactor 3.6.1

All modules that depend on reactor were already tested / compiled against 3.6.1, since it's the version
brought in by Spring Boot; however, the DGS platform BOM was still requesting an older version.

Update the DGS platform BOM to be in line with the Spring Boot version.

See: https://docs.spring.io/spring-boot/docs/current/reference/html/dependency-versions.html

graphql-dgs-platform/build.gradle.kts

@@ -84,10 +84,10 @@ dependencies {
             version { require("2.7.0") }
         }
         api("io.projectreactor:reactor-core") {
-            version { require("3.4.22") }
+            version { require("3.6.1") }
         }
         api("io.projectreactor:reactor-test"){
-            version { require("3.4.22") }
+            version { require("3.6.1") }
         }
         // CVEs
         api("org.apache.logging.log4j:log4j-to-slf4j:2.22.1") {