Upgrade to Log4j 2.13.3 in Maven tests

See gh-23935

Author: nohn

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/intTest/java/org/springframework/boot/maven/MavenBuild.java

@@ -84,7 +84,7 @@ class MavenBuild {
 		this.pomReplacements.put("project.groupId", "org.springframework.boot");
 		this.pomReplacements.put("project.artifactId", "spring-boot-maven-plugin");
 		this.pomReplacements.put("project.version", determineVersion());
-		this.pomReplacements.put("log4j2.version", "2.12.1");
+		this.pomReplacements.put("log4j2.version", "2.13.3");
 		this.pomReplacements.put("maven-jar-plugin.version", "3.2.0");
 		this.pomReplacements.put("maven-toolchains-plugin.version", "3.0.0");
 		this.pomReplacements.put("maven-war-plugin.version", "3.2.3");