fix: correct import order in self_service.py

Signed-off-by: homalozoa <nx.tardis@gmail.com>

Author: homalozoa

ch4/service/ch4_service_py/ch4_service_py/self_service.py

@@ -12,12 +12,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from rcl_interfaces.msg import Parameter
+from rcl_interfaces.srv import GetParameters
+
 import rclpy
-import rclpy.executors
 
 from rclpy.node import Node
-from rcl_interfaces.msg import Parameter
-from rcl_interfaces.srv import GetParameters
+
+import rclpy.executors
 
 
 class ServerNode(Node):