[GoalValidatorTest] corrected test for joint goal to use a value that…

… is withing the limits of the joint.

test/test_goal_validator.py

@@ -88,7 +88,7 @@ def test_single_revolute_joint_position_goal(self):
         self.validate_revolute_joint_position_goal(goal_validator, JointType.REVOLUTE)
 
     def validate_revolute_joint_position_goal(self, goal_validator, joint_type: Optional[JointType] = None):
-        goal_joint_position = -np.pi / 4
+        goal_joint_position = -np.pi / 8
         joint_name = 'l_shoulder_lift_joint'
         if joint_type is not None:
             goal_validator.register_goal(goal_joint_position, joint_type, joint_name)