o3d.io.write_point_cloud

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [X] For Python issues, I have tested with the [latest development wheel](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### My Question

when I use write_point_cloud to output my point cloud data, why is my data's precision changed?

example:

xyz_trans=np.array(xyz,dtype="float64").transpose()
print(xyz_trans)

[[ 386341.85346631845 5819822.652138979 34.5 ]
[ 386356.27239456156 5819809.186501318 35. ]
[ 386352.80354357697 5819811.8264322 35.5 ]
...
[ 386422.5859865142 5819767.698759984 60.5 ]
[ 386253.1977662458 5819811.1340125 47.5 ]
[ 386469.6175699793 5819828.59143278 73. ]]

# write pcd
pc_tr=o3d.cuda.pybind.geometry.PointCloud()
# pc_tr=o3d.geometry.PointCloud()

pc_tr.points=o3d.utility.Vector3dVector(xyz_trans)
o3d.io.write_point_cloud("pc_tr.pcd",pc_tr,True)

so when I check my pc_tr.pcd file, the result is :

386341.8535 5819822.652 34.5
386356.2724 5819809.187 35
386352.8035 5819811.826 35.5
386351.2526 5819815.201 35
386349.8963 5819812.339 35
386349.4789 5819811.904 35
386347.5385 5819807.275 34.5
386357.7001 5819818.056 35.5
386358.6379 5819814.584 36.5
386355.5006 5819816.883 35
386355.0256 5819816.894 35