Amulet of Storms effect also blocks Plane of Air lightning paralysis

Seems reasonable that it'd have this protective effect as well.

doc/xnh-changelog-9.0.md

@@ -42,7 +42,8 @@ changes:
 - Leprechauns have a one-sided grudge against gold golems and gold dragons.
 - New artifact The Amulet of Storms: a chaotic amulet of flying that grants
   shock resistance when worn and allows you to chat to hostile vortices, air
-  elementals, and storm giants to pacify them.
+  elementals, and storm giants to pacify them. It also prevents you from being
+  paralyzed by lightning on the Plane of Air.
 
 ### Interface changes
 

src/timeout.c

@@ -1829,7 +1829,8 @@ do_storms(void)
         pline("Kaboom!!!  Boom!!  Boom!!");
         incr_itimeout(&HDeaf, rn1(20, 30));
         gc.context.botl = TRUE;
-        if (!u.uinvulnerable) {
+        if (!u.uinvulnerable
+            || !(u.uamul && u.uamul->oartifact == ART_AMULET_OF_STORMS)) {
             stop_occupation();
             nomul(-3);
             gm.multi_reason = "hiding from thunderstorm";