Add --upgrade-deps to venv module
- This allows for pip + setuptools to be automatically upgraded to the latest version on PyPI
- Update documentation to represent this change

bpo-34556: Add --upgrade to venv module

Explain in the doc why PyObject_CallNoArgs() should be preferred over
other existing ways to call a function without any arguments.

Other implementation can raise MemoryError, but it can takes hours.

Mention explicitly that PyObject_CallXXX() functions raise an
exception an failure.

Add a new public PyObject_CallNoArgs() function to the C API: call a
callable Python object without any arguments.

It is the most efficient way to call a callback without any argument.
On x86-64, for example, PyObject_CallFunctionObjArgs(func, NULL)
allocates 960 bytes on the stack per call, whereas
PyObject_CallNoArgs(func) only allocates 624 bytes per call.

It is excluded from stable ABI 3.8.

Replace private _PyObject_CallNoArg() with public
PyObject_CallNoArgs() in C extensions: _asyncio, _datetime,
_elementtree, _pickle, _tkinter and readline.

Remove _dummy_thread and dummy_threading modules. These modules
were deprecated since Python 3.7 which requires threading support.

bpo-35031, bpo-35998: Reintroduce workaround on Windows and FreeBSD
in test_start_tls_server_1() of test_asyncio: disable TLS v1.3 on the
client context.

On Windows, os.dup() no longer creates an inheritable fd when handling a
character file.

The patch needed for 2.7 should make the test more stable on 3.x also.

bpo-35922: Fix RobotFileParser when robots.txt has no relevant crawl delay or request rate (GH-11791)
Co-Authored-By: Tal Einat <taleinat+github@gmail.com>

bpo-28009: Fix uuid SkipUnless logic to be based on platform programs capable of introspection (GH-12777)

uuid could try fallback methods that had no chance of working on a particular
platform, and this could cause spurious test failures, as well as degraded
performance as fallback options were tried and failed.

This fixes both the uuid module and its test's SkipUnless logic to use a
prefiltered list of techniques that may at least potentially work on that platform.

Patch by Michael Felt (aixtools).

To reflect the one we're using in production.

* Increase timeout for PGO builds in Windows release
* Fix test step failures
* Disable MinGW step properly
* Fix embeddable distro name

bpo-35537, bpo-35876: Fix also test_start_new_session() of
test_subprocess: use os.getsid() rather than os.getpgid().

In a subinterpreter, spawning a daemon thread now raises an
exception. Daemon threads were never supported in subinterpreters.
Previously, the subinterpreter finalization crashed with a Pyton
fatal error if a daemon thread was still running.

* Add _thread._is_main_interpreter()
* threading.Thread.start() now raises RuntimeError if the thread is a
  daemon thread and the method is called from a subinterpreter.
* The _thread module now uses Argument Clinic for the new function.
* Use textwrap.dedent() in test_threading.SubinterpThreadingTests

Document reference cycle and resurrected objects issues in
sys.unraisablehook() and threading.excepthook() documentation.

Fix test.support.catch_unraisable_exception(): __exit__() no longer
ignores unraisable exceptions.

Fix test_io test_writer_close_error_on_close(): use a second
catch_unraisable_exception() to catch the BufferedWriter unraisable
exception.