Element.getiterator() and the html parameter of XMLParser() were
deprecated only in the documentation (since Python 3.2 and 3.4 correspondintly).
Now using them emits a deprecation warning.
* Don’t need check_warnings any more.
Issue #29286. Run Argument Clinic to get the new faster METH_FASTCALL calling
convention for functions using "boring" positional arguments.
Manually fix _elementtree: _elementtree_XMLParser_doctype() must remain
consistent with the clinic code.
A deprecation warning no longer issued by XMLParser subclass with default
doctype() method. Direct call of doctype() now issues a warning. Parser's
doctype() now is not called if target's doctype() is called. Based on patch
by Martin Panter.