Upgrade to Spring Boot 2.4 snapshots

in order to make use of a recent change for WebMvc.fn in
Spring Framework 5.3.

See spring-iogh-6

build.gradle

@@ -1,5 +1,7 @@
+import org.springframework.boot.gradle.plugin.SpringBootPlugin
+
 plugins {
-	id 'org.springframework.boot' version '2.3.3.RELEASE' apply false
+	id 'org.springframework.boot' version '2.4.0-SNAPSHOT' apply false
 }
 
 subprojects {
@@ -14,11 +16,13 @@ subprojects {
 
 	repositories {
 		mavenCentral()
+		maven { url 'https://repo.spring.io/milestone' }
+		maven { url "https://repo.spring.io/snapshot" }
 	}
 
 	dependencyManagement {
 		imports {
-			mavenBom org.springframework.boot.gradle.plugin.SpringBootPlugin.BOM_COORDINATES
+			mavenBom SpringBootPlugin.BOM_COORDINATES
 		}
 		dependencies {
 			dependency 'com.graphql-java:graphql-java:15.0'

settings.gradle

@@ -1,3 +1,10 @@
+pluginManagement {
+	repositories {
+		mavenCentral()
+		maven { url 'https://repo.spring.io/snapshot' }
+	}
+}
+
 rootProject.name = 'spring-graphql'
 include 'spring-boot-starter-graphql-web'
 include 'spring-boot-starter-graphql-webflux'

spring-graphql-web/src/test/java/org/springframework/graphql/WebInterceptorExecutionChainTests.java

@@ -37,8 +37,7 @@
 import org.springframework.util.ResourceUtils;
 
 import static graphql.schema.idl.TypeRuntimeWiring.newTypeWiring;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
+import static org.assertj.core.api.Assertions.assertThat;
 
 /**
  * Unit tests for {@link WebInterceptorExecutionChain}.
@@ -68,8 +67,8 @@ void testInterceptorInvocation() throws Exception {
 		WebOutput webOutput = new WebInterceptorExecutionChain(createGraphQL(), interceptors)
 				.execute(webInput).block();
 
-		assertEquals(":pre1:pre2:pre3:post3:post2:post1", sb.toString());
-		assertTrue(webOutput.isDataPresent());
+		assertThat(sb.toString()).isEqualTo(":pre1:pre2:pre3:post3:post2:post1");
+		assertThat(webOutput.isDataPresent()).isTrue();
 	}
 
 	private static GraphQL createGraphQL() throws Exception {