In `plate_solve()` use new WCS API

plate_solve() is using all_pix2world() which appears to be part of the legacy WCS API. I should probably be using pixel_to_world() from the new API.

Relevant code:

track/track/plate_solve.py

Lines 86 to 91 in 86d3686

    
           center_coord = wcs_header.all_pix2world( 
        
               (frame_width - 1) / 2.0, 
        
               (frame_height - 1) / 2.0, 
        
               0, 
        
               ra_dec_order=True, 
        
           )

New API: https://docs.astropy.org/en/stable/wcs/wcsapi.html
pixel_to_world(): https://docs.astropy.org/en/stable/api/astropy.wcs.wcsapi.BaseHighLevelWCS.html#astropy.wcs.wcsapi.BaseHighLevelWCS.pixel_to_world

	center_coord = wcs_header.all_pix2world(
	(frame_width - 1) / 2.0,
	(frame_height - 1) / 2.0,
	0,
	ra_dec_order=True,
	)