Merge branch '2.3.x' into 2.4.x

Closes gh-26724

Author: snicoll

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/logback/LogbackLoggingSystem.java

@@ -343,7 +343,7 @@ public void run() {
 	@Order(Ordered.LOWEST_PRECEDENCE)
 	public static class Factory implements LoggingSystemFactory {
 
-		private static final boolean PRESENT = ClassUtils.isPresent("ch.qos.logback.core.Appender",
+		private static final boolean PRESENT = ClassUtils.isPresent("ch.qos.logback.classic.LoggerContext",
 				Factory.class.getClassLoader());
 
 		@Override