Update to crrect match spectation.

On the problem specification for this exercise, we should follow what is
defined. Matching the input error first in case both are invalid.

For All your base exercise, we need it's valid to return input or output error when both are provided.
This commit allows both to be returned from the tested function

exercises/practice/all-your-base/test/all_your_base_test.exs

@@ -104,6 +104,6 @@ defmodule AllYourBaseTest do
 
   @tag :pending
   test "convert both bases are negative" do
-    assert AllYourBase.convert([1], -2, -7) == {:error, "output base must be >= 2"}
+    assert AllYourBase.convert([1], -2, -7) == {:error, "input base must be >= 2"}
   end
 end