Remove no longer needed gzip-win32 dependency

mentioned in merge request !1 (merged)

mentioned in commit gioele/gzip@83d694dd

mentioned in commit cf0f8bcd

mentioned in commit gioele/gzip@f7203dcc

mentioned in commit gioele/gzip@eecd45ed

mentioned in commit gioele/gzip@fb6cc47f

mentioned in commit gioele/gzip@f30ac496

mentioned in commit gioele/gzip@081ca8e3

mentioned in commit debian/gzip@d42fa01e