Upgrade to Netty 4.1.52.Final

Closes gh-23313

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

@@ -1237,7 +1237,7 @@ bom {
 			]
 		}
 	}
-	library("Netty", "4.1.51.Final") {
+	library("Netty", "4.1.52.Final") {
 		group("io.netty") {
 			imports = [
 				"netty-bom"

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/reactive/server/AbstractReactiveWebServerFactoryTests.java

@@ -268,7 +268,11 @@ public abstract class AbstractReactiveWebServerFactoryTests {
 		Mono<String> result = client.post().uri("/test").contentType(MediaType.TEXT_PLAIN)
 				.body(BodyInserters.fromValue("Hello World")).exchange()
 				.flatMap((response) -> response.bodyToMono(String.class));
-		StepVerifier.create(result).expectError(SSLException.class).verify(Duration.ofSeconds(10));
+		StepVerifier.create(result).expectErrorSatisfies((exception) -> {
+			if (!(exception instanceof SSLException)) {
+				assertThat(exception).hasCauseInstanceOf(SSLException.class);
+			}
+		}).verify(Duration.ofSeconds(10));
 	}
 
 	protected WebClient.Builder getWebClient(int port) {