pyx.build: v↑ setuptools_dso (2.7 -> 2.8)

This fixes linking to editable pygolang install on Windows.
See https://github.com/mdavidsaver/setuptools_dso/commit/fca6f29e and
https://github.com/mdavidsaver/setuptools_dso/pull/25 for details.

Without this fix e.g. test_pyx_build was also failing:

    platform win32 -- Python 3.10.11, pytest-7.3.1, pluggy-1.0.0 -- Z:\home\kirr\src\tools\go\pygo-win\1.wenv\Scripts\python.exe
    cachedir: .pytest_cache
    rootdir: Z:\home\kirr\src\tools\go\pygo-win\pygolang
    collecting 3 items
    collected 3 items

    golang/pyx/build_test.py::test_pyx_build running build_ext
    skipping 'pyxuser\test.cpp' Cython extension (up-to-date)
    building 'pyxuser.test' extension
    Z:\home\kirr\src\tools\go\pygo-win\BuildTools\vc\tools\msvc\14.35.32215\bin\Hostx64\x64\cl.exe /c /nologo /O2 /W3 /GL /DNDEBUG /MD -IZ:\home\kir
    r\src\tools\go\pygo-win\pygolang -IZ:\home\kirr\src\tools\go\pygo-win\pygolang\golang\_compat\windows -IZ:\home\kirr\src\tools\go\pygo-win\1.wen
    v\include\site\python3.10 -IZ:\home\kirr\src\tools\go\pygo-win\1.wenv\include "-IC:\Program Files\Python310\include" "-IC:\Program Files\Python3
    10\Include" -Iz:\home\kirr\src\tools\go\pygo-win\BuildTools\vc\tools\msvc\14.35.32215\include -Iz:\home\kirr\src\tools\go\pygo-win\BuildTools\ki
    ts\10\include\10.0.22000.0\shared -Iz:\home\kirr\src\tools\go\pygo-win\BuildTools\kits\10\include\10.0.22000.0\ucrt -Iz:\home\kirr\src\tools\go\
    pygo-win\BuildTools\kits\10\include\10.0.22000.0\um -Iz:\home\kirr\src\tools\go\pygo-win\BuildTools\kits\10\include\10.0.22000.0\winrt /EHsc /Tp
    pyxuser\test.cpp /Fobuild\temp.win-amd64-cpython-310\Release\pyxuser\test.obj /std:c++20 /EHc- /EHsr
    cl : Command line warning D9025 : overriding '/EHc' with '/EHc-'
    test.cpp
    ...
    Z:\home\kirr\src\tools\go\pygo-win\BuildTools\vc\tools\msvc\14.35.32215\bin\Hostx64\x64\link.exe /nologo /INCREMENTAL:NO /LTCG /DLL /MANIFEST:EM
    BED,ID=2 /MANIFESTUAC:NO /LIBPATH:Z:\home\kirr\src\tools\go\pygo-win\pygolang\golang\runtime "/LIBPATH:C:\Program Files\Python310\libs" "/LIBPAT
    H:C:\Program Files\Python310" /LIBPATH:z:\home\kirr\src\tools\go\pygo-win\BuildTools\vc\tools\msvc\14.35.32215\lib\x64 /LIBPATH:z:\home\kirr\src
    \tools\go\pygo-win\BuildTools\kits\10\lib\10.0.22000.0\ucrt\x64 /LIBPATH:z:\home\kirr\src\tools\go\pygo-win\BuildTools\kits\10\lib\10.0.22000.0\
    um\x64 libgolang.lib /EXPORT:PyInit_test build\temp.win-amd64-cpython-310\Release\pyxuser\test.obj /OUT:build\lib.win-amd64-cpython-310\pyxuser\
    test.cp310-win_amd64.pyd /IMPLIB:build\temp.win-amd64-cpython-310\Release\pyxuser\test.cp310-win_amd64.lib
    LINK : fatal error LNK1181: cannot open input file 'libgolang.lib'		<-- NOTE
    error: command 'Z:\\home\\kirr\\src\\tools\\go\\pygo-win\\BuildTools\\vc\\tools\\msvc\\14.35.32215\\bin\\Hostx64\\x64\\link.exe' failed with exi
    t code 1181
    FAILED

    ========================== FAILURES ===========================
    _______________________ test_pyx_build ________________________

        def test_pyx_build():
            pyxuser = testprog + "/golang_pyx_user"
    >       pyrun(["setup.py", "build_ext", "-i"], cwd=pyxuser)

    golang\pyx\build_test.py:31:
    _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

    argv = ['setup.py', 'build_ext', '-i'], stdin = None, stdout = None, stderr = None
    kw = {'cwd': 'Z:\\home\\kirr\\src\\tools\\go\\pygo-win\\pygolang\\golang\\pyx/testprog/golang_pyx_user'}, retcode = 1

        def pyrun(argv, stdin=None, stdout=None, stderr=None, **kw):

            retcode, stdout, stderr = _pyrun(argv, stdin=stdin, stdout=stdout, stderr=stderr, **kw)
            if retcode:
    >           raise RuntimeError(' '.join(argv) + '\n' + (stderr and str(stderr) or '(failed)'))
    E           RuntimeError: setup.py build_ext -i
    E           (failed)

    golang\golang_test.py:1771: RuntimeError

pyproject.toml

 [build-system]
-requires = ["setuptools", "wheel", "setuptools_dso >= 2.7", "cython", "gevent"]
+requires = ["setuptools", "wheel", "setuptools_dso >= 2.8", "cython", "gevent"]

setup.py

@@ -155,7 +155,7 @@ class develop(XInstallGPython, _develop):
 # requirements of packages under "golang." namespace
 R = {
     'cmd.pybench':      {'pytest'},
-    'pyx.build':        {'setuptools', 'wheel', 'cython', 'setuptools_dso >= 2.7'},
+    'pyx.build':        {'setuptools', 'wheel', 'cython', 'setuptools_dso >= 2.8'},
     'x.perf.benchlib':  {'numpy'},
 }
 # TODO generate `a.b -> a`, e.g. x.perf = join(x.perf.*); x = join(x.*)
@@ -317,7 +317,7 @@ setup(
 
     install_requires = ['gevent', 'six', 'decorator', 'Importing;python_version<="2.7"',
                         # only runtime part: for dylink_prepare_dso
-                        'setuptools_dso >= 2.7',
+                        'setuptools_dso >= 2.8',
                         # pyx.build -> setuptools_dso uses multiprocessing
                         # setuptools_dso uses multiprocessing only on Python3, and only on systems where
                         # mp.get_start_method()!='fork', while geventmp does not work on windows.