[io grant] Remove IO::Handle.z

IO::Handle never had this method.

Author: zoffixznet

doc/Type/IO/Handle.pod6

@@ -110,12 +110,6 @@ Returns C<Bool::True> if the invocant is a path and executable.
 
 Returns C<Bool::True> if the invocant is a path, executable, read and writable.
 
-=head2 method z
-
-    method z(--> Bool)
-
-Returns C<Bool::True> if the invocant is a path and the size is 0.
-
 =head2 method lines
 
     method lines($limit = Inf)