Update psexportedmethods.inc

Had forgotten to include "64" to the line:
AddFunction(@ps_ConvertTime,'procedure ConvertTime64(time: int64; var y, m, w, d, h, min, s: integer);');

Specifically here:
@ps_ConvertTime[64]

- Thus, the pull req to update this to say 64. (Other files containing method were checked too, and didn't include this mistake)