Issue #22346: also include asyncio PEP 411 notice in 3.4

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branch : 3.4
Issue #22295: Adopt 'python -m pip' as the preferred invocation

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branch : 3.4
Issue #19524: Fixed resource leak in the HTTP connection when an invalid
response is received.  Patch by Martin Panter.

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branch : 3.4
Issue #22131: Fixed a bug in handling an error occured during reading from
a pipe in _ipconfig_getnode().

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branch : 3.4
Issue #22226: Added private function _splitdict() in the Tkinter module.

First letter no longer is stripped from the "status" key in
the result of Treeview.heading().

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branch : 3.4
remove various dead version checks (closes #22349)

Patch from Thomas Kluyver.

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branch : 3.4