Update to test-fixture

An update to test-fixtures was required to handle setup code. Specifically, LET* and variable loading from LET*:

(create-tests :setup-let-and-variable-load
 (:setup  ((true t) (not-false nil))
   (setf not-false true))

 (:tests
   (test-bind-form2 (assert-true not-false))
   (test-bind-form3 (assert-true not-false))))

(create-tests :setup-let-and-use-variables
 (:setup ((lister (make-list 0))
          (lister-with-push (push 'hello lister)))