yampa-test: Add version bounds to base. Refs #320.

Hackage is complaining that yampa-test does not specify an upper bound
on base. This is preventing yampa-test from being uploaded to hackage.

This commit adds version bounds to base, consistent with other
components in the same cabal file.

yampa-test/yampa-test.cabal

@@ -163,5 +163,5 @@ test-suite space
       False
   else
     build-depends:
-        base
+        base  >= 4 && < 5
       , Yampa