Fix some issues reported by Gradle about the build script

Author: forax

build.gradle

@@ -32,7 +32,7 @@ buildscript {
 }
 
 plugins { id 'com.diffplug.spotless' version "6.23.3" apply false }
-plugins { id 'me.champeau.jmh' version '0.6.8' apply false }
+plugins { id 'me.champeau.jmh' version '0.7.2' apply false }
 plugins { id 'org.sonarqube' version '4.3.1.3277' apply false }
 
 description = 'ASM, a very small and fast Java bytecode manipulation framework'
@@ -54,8 +54,10 @@ subprojects {
   repositories { mavenCentral() }
   apply plugin: 'java-library'
   apply plugin: 'jacoco'
-  sourceCompatibility = '11'
-  targetCompatibility = '11'
+  java {
+    sourceCompatibility = '11'
+    targetCompatibility = '11'
+  }
   test { useJUnitPlatform() }
   ext.provides = []  // The provided java packages, e.g. ['org.objectweb.asm']
   ext.requires = []  // The required Gradle projects, e.g. [':asm-test']
@@ -168,8 +170,10 @@ project(':tools') {
 
 project(':tools:retrofitter') {
   description = "JDK 1.5 class retrofitter based on ${rootProject.description}"
-  sourceCompatibility = '11'
-  targetCompatibility = '11'
+  java {
+    sourceCompatibility = '11'
+    targetCompatibility = '11'
+  }
   // TODO: this compiles asm twice (here and in :asm).
   sourceSets.main.java.srcDirs += project(':asm').sourceSets.main.java.srcDirs
 }