Molex 73251 2120 pad fix

This connector, already in the library, is an edge connector. In existing footprint, pads reach the PCB edge

With this MR, there is a 0.5mm distance between pads and the connector body.

Manufacturers often require this distance for a V-cut scoring. Example:

• https://www.eurocircuits.com/copper-and-the-board-edge/
  • 0.25 mm on outer layers with breakrouting
  • 0.40 mm on inner layers with breakrouting
  • 0.45 mm on all layers with V-cut scoring.

This shouldn't affect solderability of the connector, because leads are much bigger.

3D prefix is changed to KiCad7 too.