More qualified import of zify.ssrZ

Without a qualified import `coq-mathcomp-apery` is incompatible with `coq-mathcomp-word`. See also jasmin-lang/coqword#15

theories/rat_of_Z.v

@@ -1,6 +1,6 @@
 Require Import ZArith.
 From mathcomp Require Import all_ssreflect all_algebra.
-From mathcomp Require Export ssrZ.
+From mathcomp.zify Require Export ssrZ.
 Require Import tactics.
 
 Set Implicit Arguments.