Merge branch 'fix/64-execute-method-of-commandhandler-is-not-abstract' into 'main'

Change execute method in CommandHandler to be abstract

Closes #64

See merge request cs108-fs26/Gruppe-13!91

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/command/execution/CommandHandler.java

@@ -52,5 +52,5 @@ public abstract class CommandHandler<T extends Request> {
      *
      * @param request the request to execute, of type T
      */
-    public void execute(T request) {}
+    public abstract void execute(T request);
 }