don't link dependencies with conflicts

The new anyzig formula depends on the zig formula, but, it also
conflicts_with it because they both install `zig` binaries. This works
fine with brew but test-bot is failing because it's linking the dependency
before installing, even with the conflict. The fix is to disable linking
dependencies that are also marked as conflicts.

Author: marler8997

lib/tests/formulae.rb

@@ -158,6 +158,7 @@ def setup_formulae_deps_instances(formula, formula_name, args:)
           link_formula = Formulary.factory(name)
           next if link_formula.keg_only?
           next if link_formula.linked_keg.exist?
+          next if unlink_formulae.include?(name)
 
           test "brew", "link", name
         end