Fix deprecation warning in paramater declaration

Updated the paramater declaration in `publisher_forward_position_controller` to resolve a deprecation warning.

Changes Made:
- Replaced `self.declare_parameter(name)` with `self.declare_parameter(name, descriptor=ParameterDescriptor(dynamic_typing=True))`

Fixes: #1239

ros2_controllers_test_nodes/ros2_controllers_test_nodes/publisher_forward_position_controller.py

@@ -17,6 +17,7 @@
 
 import rclpy
 from rclpy.node import Node
+from rcl_interfaces.msg import ParameterDescriptor
 
 from std_msgs.msg import Float64MultiArray
 
@@ -37,7 +38,7 @@ def __init__(self):
         # Read all positions from parameters
         self.goals = []
         for name in goal_names:
-            self.declare_parameter(name)
+            self.declare_parameter(name, descriptor=ParameterDescriptor(dynamic_typing=True))
             goal = self.get_parameter(name).value
             if goal is None or len(goal) == 0:
                 raise Exception(f'Values for goal "{name}" not set!')