Autoplanner will take number of pilots into account when planning purchases

- Added expected_pilots_next_turn() to Squadron. The procurement AI now correctly compares to it when evaluating if planes should be bought, instead of the maximum possible number of pilots.
- Added replenish_rate method to squadron.py to prevent expected_pilots_next_turn from returning an incorrect (too large) number when replenish rate > pilots required.
#1837

game/procurement.py

@@ -185,6 +185,14 @@ class ProcurementAi:
     ) -> Tuple[float, bool]:
         for squadron in squadrons:
             price = squadron.aircraft.price * quantity
+            # Final check to make sure the number of aircraft won't exceed the number of available pilots
+            # after fulfilling this aircraft request.
+            if (
+                squadron.pilot_limits_enabled
+                and squadron.expected_size_next_turn + quantity
+                > squadron.expected_pilots_next_turn
+            ):
+                continue
             if price > budget:
                 continue