use java 21

Author: steve4744

pom.xml

@@ -9,8 +9,8 @@
 
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-    <maven.compiler.source>17</maven.compiler.source>
-    <maven.compiler.target>17</maven.compiler.target>
+    <maven.compiler.source>21</maven.compiler.source>
+    <maven.compiler.target>21</maven.compiler.target>
   </properties>
 
   <licenses>