Add missing functions to header (#9730)

Co-authored-by: Ivan Levkivskyi <[email protected]>

Author: ilevkivskyi

mypyc/lib-rt/CPy.h

@@ -377,6 +377,8 @@ PyObject *CPyStr_GetItem(PyObject *str, CPyTagged index);
 PyObject *CPyStr_Split(PyObject *str, PyObject *sep, CPyTagged max_split);
 PyObject *CPyStr_Append(PyObject *o1, PyObject *o2);
 PyObject *CPyStr_GetSlice(PyObject *obj, CPyTagged start, CPyTagged end);
+bool CPyStr_Startswith(PyObject *self, PyObject *subobj);
+bool CPyStr_Endswith(PyObject *self, PyObject *subobj);
 
 
 // Set operations