Replace PY_TYPE_CHECK and IS_INSTANCE by isinstance

<div id="comment:0"></div>



Depends on #17740

Component: **cython**

Author: **Jeroen Demeyer**

Branch/Commit: **[`4fcee82`](https://github.com/sagemath/sagetrac-mirror/commit/4fcee8214e0136d5c02ac7e528f65925740d4db7)**

Reviewer: **R. Andrew Ohana**

_Issue created by migration from https://trac.sagemath.org/ticket/17800_

