Merge branch '2.4.x'

Closes gh-26412

gradle/wrapper/gradle-wrapper.properties

 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.8.3-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.9-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/junit/GradleCompatibilityExtension.java

@@ -51,7 +51,7 @@ final class GradleCompatibilityExtension implements TestTemplateInvocationContex
 			GRADLE_VERSIONS = Arrays.asList("7.0");
 		}
 		else {
-			GRADLE_VERSIONS = Arrays.asList("current", "6.9-rc-2", "7.0");
+			GRADLE_VERSIONS = Arrays.asList("6.8.3", "current", "7.0");
 		}
 	}