🔍 Allow LMR when in check

[eduherminio]

Suggested by Martin Novák, Motor's author.

Test  | search/lmr-allow-check
Elo   | 4.73 +- 3.48 (95%)
SPRT  | 8.0+0.08s Threads=1 Hash=32MB
LLR   | 2.91 (-2.25, 2.89) [0.00, 3.00]
Games | N: 23042 W: 7114 L: 6800 D: 9128
Penta | [798, 2555, 4554, 2763, 851]
https://openbench.lynx-chess.com/test/231/