Mookie Betts and Red Sox putting the Yankees on notice

OSTON — Mookie Betts and the Red Sox gave the Yankees and Brian Cashman a booming message Friday night at Fenway Park: You had better trade for another starting pitcher. Betts slammed three home runs off James Paxton in his first three at-bats as the Red Sox cruised to a 10-5 victory. If you’re counting,…