bpo-43244: GitHub Action builds Python in debug mode on Windows

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The debug mode catchs more bugs but is slower.

https://bugs.python.org/issue43244

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cc @zooba @zware @pablogsal

I didn't check yet if this change makes the CI way slower or not.

I wrote this PR since the Windows x64 job of GitHub Actions didn't catch the build error about Py_DebugFlag in test_peg_generator in my previous PR:
#24912 (comment)

Hopefully, we have at least one Windows buildbot running in release mode: https://buildbot.python.org/all/#/builders/405

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Oh, test_peg_generator failed. I rebased my PR on top of my commit 57d0a87 fix.

test_locale also fails, I don't know why and I don't see why it only fails in debug mode:

ERROR: test_getsetlocale_issue1813 (test.test_locale.TestMiscellaneous)
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Traceback (most recent call last):
  File "D:\a\cpython\cpython\lib\test\test_locale.py", line 567, in test_getsetlocale_issue1813
    locale.setlocale(locale.LC_CTYPE, loc)
  File "D:\a\cpython\cpython\lib\locale.py", line 610, in setlocale
    return _setlocale(category, locale)
locale.Error: unsupported locale setting

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The job still fails with:

ERROR: test_getsetlocale_issue1813 (test.test_locale.TestMiscellaneous)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "D:\a\cpython\cpython\lib\test\test_locale.py", line 567, in test_getsetlocale_issue1813
    locale.setlocale(locale.LC_CTYPE, loc)
  File "D:\a\cpython\cpython\lib\locale.py", line 610, in setlocale
    return _setlocale(category, locale)
locale.Error: unsupported locale setting

With test_locale re-run in verbose mode, "the total tests duration is 19 min 41 sec.

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Oh, test_locale failure seems to be known since 2019: https://bugs.python.org/issue37945

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Without this PR (Python built in release mode), tests take 12 min 19 sec on Windows x64. It should be compared with 19 min 41 sec with this PR. So this PR adds 7 minutes to the CI, it's quite signifiant (1.6x slower).

I'm not sure that I would like to make the CI slower on all PRs just because once per year there is a bug not catched by the pre-commit PR. I close the PR.