build: Java版本升级到21

novel-admin/pom.xml

@@ -19,7 +19,7 @@
     </parent>
 
     <properties>
-        <java.version>17</java.version>
+        <java.version>21</java.version>
         <velocity.version>1.7</velocity.version>
         <shardingsphere-jdbc.version>5.5.1</shardingsphere-jdbc.version>
     </properties>

pom.xml

@@ -27,7 +27,7 @@
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
-        <java.version>17</java.version>
+        <java.version>21</java.version>
         <maven.test.skip>true</maven.test.skip>
         <mysql.version>8.0.29</mysql.version>
         <mybatis.version>2.1.4</mybatis.version>