update nacos version to 0.2.1

update nacos version to 0.2.1.  change default port. 8080 -> 8848. fix port conflict.

sentinel-extension/sentinel-datasource-nacos/pom.xml

@@ -13,7 +13,7 @@
     <packaging>jar</packaging>
 
     <properties>
-        <nacos.version>0.2.0</nacos.version>
+        <nacos.version>0.2.1</nacos.version>
     </properties>
 
     <dependencies>
@@ -28,4 +28,4 @@
             <version>${nacos.version}</version>
         </dependency>
     </dependencies>
-</project>
+</project>