Fix [imageCoCenter](https://github.com/lsst-ts/ts_wep/blob/40a62fd336ee7d150afa5ae4c7392b7001c6cfaf/python/lsst/ts/wep/cwfs/CompensableImage.py#L273) in `ts_wep`. In principle, the radial shift should be 0 for `paraxial` opticalModel, yet currently there is a radial shift that's only dependent on the distance from the center of the field of view (as in the attached image, illustrating the value of `radialShift` in https://github.com/lsst-ts/ts_wep/blob/40a62fd336ee7d150afa5ae4c7392b7001c6cfaf/python/lsst/ts/wep/cwfs/CompensableImage.py#L310 given offset of 1.5 mm and pixels size 1e-5 m (=10 microns)).