_1password: Fix Darwin Builds

The latest update to 1.9.1 broke builds on darwin, due to some paths
changing in the unpacked darwin package.

This updates the darwin unpackPhase to use the updated path.

pkgs/applications/misc/1password/default.nix

@@ -25,7 +25,7 @@ stdenv.mkDerivation rec {
 
   unpackPhase = lib.optionalString stdenv.isDarwin ''
     xar -xf $src
-    zcat Payload | cpio -i
+    zcat op.pkg/Payload | cpio -i
   '';
 
   installPhase = ''