fix: numpy float deprectation

[Sjouks]

Latest numpy release deprecates np.float, see: https://numpy.org/doc/stable/release/1.24.0-notes.html#expired-deprecations

This MR aims to solve this deprecation issue by replacing np.float by np.float32.

[DeboBurro]

we have this issue too. discussed as well in StackOverflow

  File "/root/catkin_ws/install/lib/python3/dist-packages/ros_numpy/point_cloud2.py", line 224, in <module>
    def get_xyz_points(cloud_array, remove_nans=True, dtype=np.float):
  File "/root/.local/lib/python3.8/site-packages/numpy/__init__.py", line 284, in __getattr__
    raise AttributeError("module {!r} has no attribute "
AttributeError: module 'numpy' has no attribute 'float'

The only thing I am not sure about here is that should be float64 or float32?

[SimonCBell]

We have this issue too. Would be great to get it fixed!

[juliangaal]

The only thing I am not sure about here is that should be float64 or float32?

To my knowledge, the points in PointCloud2 are of type float, not double, so float32 makes more sense

[cjue]

Isn't this issues solved since #39 was merged?