actually compiling JAVA 21

also changing the artifact ID to disconnect from old version

README.md

@@ -1,12 +1,11 @@
 # lintstone
 There is no Thread Thlintstone. Lintstone is a simple actor framework. nough said.
 
-NOTE: this is the java 11 compatibility branch. This is probably not compatible with JAVA 8
 
 ```xml
 <dependency>
     <groupId>io.github.paxel</groupId>
-    <artifactId>lintstone-java11</artifactId>
+    <artifactId>lintstone</artifactId>
     <version><!-- version see release page -->></version>
 </dependency>
 ```

pom.xml

@@ -4,16 +4,16 @@
     <modelVersion>4.0.0</modelVersion>
 
     <groupId>io.github.paxel</groupId>
-    <artifactId>lintstone</artifactId>
+    <artifactId>lintstone-actor-system</artifactId>
     <version>2.0.0-SNAPSHOT</version>
 
     <name>LintStone - Actor System</name>
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <maven.compiler.source>11</maven.compiler.source>
-        <maven.compiler.target>11</maven.compiler.target>
-        <maven.compiler.release>11</maven.compiler.release>
+        <maven.compiler.source>21</maven.compiler.source>
+        <maven.compiler.target>21</maven.compiler.target>
+        <maven.compiler.release>21</maven.compiler.release>
     </properties>
     <description>Lightweight Actor Framework</description>
     <url>https://github.com/paxel/lintstone</url>