[Retros] another 8th rank mate

[andrew buchanan]

Hi Nicolas,

It's possible to shorten the gxfB by 1.0...

gxfB
1rbnBbnr/pppkp2p/4p3/4P2Q/8/6p1/PPPP1P1P/RNB1K1NR
PG in 19.0
"Nicolas Dupont & Andrew Buchanan" ? :-)

This also is one of the rare examples for this task with no extraneous
promoted pieces.

Cheers,
Andrew.