Added missing dependency: it was possible to play Fort Magma

as part of the alltracks.challenge, without having unlocked
Fort Magma first (and in the worst case: you happen to fulfill
the fortmagma challenge while doing the alltrack challenge,
so you have just driven Fort Magma, then you get the message
that you have unlocked Fort Magma).


git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@7557 178a84e3-b1eb-0310-8ba1-8eac791a3b58

data/challenges/alltracks.challenge

@@ -5,7 +5,7 @@
     name="Win the At World's End Grand Prix"
     description="Come first in the At World's End Grand Prix with 3 Expert AI karts."
     unlock-gp="alltracks"
-    depend-on="islandfollow"
+    depend-on="islandfollow fortmagma"
     major="grandprix"
     minor="quickrace"
     gp="atworldsend"