test: remove a trailing space

Author: kou

test/fiddle/test_pointer.rb

@@ -45,7 +45,7 @@ def test_malloc_block
     end
 
     def test_malloc_block_no_free
-      assert_raise ArgumentError do 
+      assert_raise ArgumentError do
         Pointer.malloc(10) { |ptr| }
       end
     end