build(deps): bump Gradle from 7.4.2 to 8.9

buildSrc/build.gradle.kts

@@ -9,10 +9,6 @@ java {
     }
 }
 
-kotlinDslPluginOptions {
-    jvmTarget.set("11") // TODO: remove when migrating to Gradle 8
-}
-
 repositories {
     mavenCentral()
 }

buildSrc/src/main/kotlin/tool/generator/ast/task/GenerateAst.kt

@@ -74,7 +74,7 @@ open class GenerateAst : DefaultTask() {
             // We create a unique folder to store files generated for the header.
             // This is necessary because when we store all headers in the same directory,
             // their AST dump can overlap with each other.
-            val astBuildDir = File("${project.buildDir}/generated/ast/$headerHash")
+            val astBuildDir = File("${project.layout.buildDirectory}/generated/ast/$headerHash")
             astBuildDir.mkdirs()
 
             // Move the header content to the temp file to make an ast-dump of it.

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.4.2-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.9-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists