Upgrade to Jetty Reactive HTTPClient 1.1.8

Closes gh-26546

spring-boot-project/spring-boot-dependencies/build.gradle

@@ -873,7 +873,7 @@ bom {
 			]
 		}
 	}
-	library("Jetty Reactive HTTPClient", "1.1.7") {
+	library("Jetty Reactive HTTPClient", "1.1.8") {
 		prohibit("[2,)") {
 			because "it uses the jakarta.* namespace"
 		}