Move blank in pin operator koan

lib/koans/07_pattern_matching.ex

@@ -13,8 +13,8 @@ defmodule PatternMatching do
 
   koan "A pattern can also be strict" do
     a = 1
-    assert_raise ___, fn() ->
+    assert_raise MatchError, fn() ->
-      ^a = 2
+      ^a = ___
     end
   end
 

test/koans/patterns_koans_test.exs

@@ -6,7 +6,7 @@ defmodule PatternsTests do
     answers = [
       1,
       2,
-      MatchError,
+      2,
       {:multiple, [1, [2,3,4]]},
       [1,2,3,4],
       3,