Add jetty-server to classpath for integration test

This commit works around a problem with deploying Boot apps to Wildfly
for integration testing while we investigate the root cause.

See gh-20876

spring-boot-tests/spring-boot-deployment-tests/build.gradle

@@ -10,6 +10,7 @@ dependencies {
 	implementation(project(":spring-boot-project:spring-boot-starters:spring-boot-starter-web")) {
 		exclude group: "org.hibernate.validator"
 	}
+	implementation("org.eclipse.jetty:jetty-server")
 
 	intTestImplementation(enforcedPlatform(project(path: ":spring-boot-project:spring-boot-parent")))
 	intTestImplementation(project(":spring-boot-project:spring-boot-starters:spring-boot-starter-test"))