Increase default bomb countdown

Because of how the countdown works, the fuse was one tick shorter than intended;
this should fix that and allow players to push a lit bomb exactly once before
having to retreat

modules/game/actors.scm

@@ -357,7 +357,7 @@
   (define alive? (spawn ^cell #t))
   (define countdown (spawn ^cell -1))
   (define pushed? (spawn ^cell))
-  (define* (light-fuse #:optional (time 2))
+  (define* (light-fuse #:optional (time 3))
     ($ countdown time))
   (match-lambda*
     (('type) 'bomb)