Upgrade Gradle and Java toolchain to latest versions (#186)

```release-note
None
```

Author: ruibaby

build.gradle

@@ -1,22 +1,29 @@
 plugins {
     id 'java'
-    id "io.freefair.lombok" version "8.0.1"
-    id "com.github.node-gradle.node" version "7.0.2"
-    id "run.halo.plugin.devtools" version "0.0.7"
+    id "io.freefair.lombok" version "8.14"
+    id "com.github.node-gradle.node" version "7.1.0"
+    id "run.halo.plugin.devtools" version "0.6.2"
 }
 
 group 'run.halo.comment.widget'
-sourceCompatibility = JavaVersion.VERSION_17
+
+java {
+    toolchain {
+        languageVersion = JavaLanguageVersion.of(21)
+    }
+}
+
+tasks.withType(JavaCompile).configureEach {
+    options.encoding = "UTF-8"
+    options.release = 21
+}
 
 repositories {
     mavenCentral()
-    maven { url 'https://s01.oss.sonatype.org/content/repositories/releases' }
-    maven { url 'https://s01.oss.sonatype.org/content/repositories/snapshots/' }
-    maven { url 'https://repo.spring.io/milestone' }
 }
 
 dependencies {
-    implementation platform('run.halo.tools.platform:plugin:2.13.0-SNAPSHOT')
+    implementation platform('run.halo.tools.platform:plugin:2.21.0')
     compileOnly 'run.halo.app:api'
 
     testImplementation 'run.halo.app:api'

gradle/wrapper/gradle-wrapper.jar

@@ -1,6 +1,7 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.0-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.0.0-bin.zip
 networkTimeout=10000
+validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

gradle/wrapper/gradle-wrapper.properties

@@ -1,11 +1 @@
-pluginManagement {
-    repositories {
-        maven { url 'https://s01.oss.sonatype.org/content/repositories/releases' }
-        maven { url 'https://maven.aliyun.com/repository/gradle-plugin' }
-        maven { url 'https://maven.aliyun.com/repository/spring-plugin' }
-        maven { url 'https://repo.spring.io/milestone' }
-        gradlePluginPortal()
-    }
-}
 rootProject.name = 'plugin-comment-widget'
-

gradlew

@@ -8,7 +8,7 @@ metadata:
     "store.halo.run/app-id": "app-YXyaD"
 spec:
   enabled: true
-  requires: ">=2.20.0"
+  requires: ">=2.21.0"
   author:
     name: Halo
     website: https://github.com/halo-dev