build(jib): 更新基础镜像版本

- 将 baseImage属性从 "docker://gewuyou/liberica-openjdk-debian-nc" 修改为 "docker://gewuyou/liberica-openjdk-debian-nc:21"
- 此更新统一了基础镜像版本，确保构建的一致性和稳定性

buildSrc/src/main/kotlin/org/jcnc/llmx/plugin/jib/entity/JibProject.kt

@@ -23,7 +23,7 @@ data class JibProject(
     var imageName: String = "",
     var version: String = "latest",
     var permissions: Map<String, String> = mapOf("/entrypoint.sh" to "755"),
-    var baseImage: String = "docker://gewuyou/liberica-openjdk-debian-nc"
+    var baseImage: String = "docker://gewuyou/liberica-openjdk-debian-nc:21"
 ) {
     init {
         if (imageName.isBlank()) {