[BUG] sporadic matplotlib tkinter failures on windows

[fkiraly]

There are sporadic failures related to matplotlib tkinter on windows, example traceback below.

These are sporadic and occur in perhaps one in 10-50 runs currently.

This is reminiscent of the following sporadic failure in sktime we had a while ago: sktime/sktime#2066, which looks like the same problem on superficial glance.
On sktime, I believe we never really diagnosed the issue, and simply added test skips on windows.

Example traceback, from https://github.com/sktime/pytorch-forecasting/actions/runs/12620582347/job/35166454483?pr=1746:

pytorch_forecasting\models\base_model.py:1231: in plot_prediction
    fig, ax = plt.subplots()
C:\hostedtoolcache\windows\Python\3.12.8\x64\Lib\site-packages\matplotlib\pyplot.py:1775: in subplots
    fig = figure(**fig_kw)
C:\hostedtoolcache\windows\Python\3.12.8\x64\Lib\site-packages\matplotlib\pyplot.py:1042: in figure
    manager = new_figure_manager(
C:\hostedtoolcache\windows\Python\3.12.8\x64\Lib\site-packages\matplotlib\pyplot.py:552: in new_figure_manager
    return _get_backend_mod().new_figure_manager(*args, **kwargs)
C:\hostedtoolcache\windows\Python\3.12.8\x64\Lib\site-packages\matplotlib\backend_bases.py:3501: in new_figure_manager
    return cls.new_figure_manager_given_figure(num, fig)
C:\hostedtoolcache\windows\Python\3.12.8\x64\Lib\site-packages\matplotlib\backend_bases.py:3506: in new_figure_manager_given_figure
    return cls.FigureCanvas.new_manager(figure, num)
C:\hostedtoolcache\windows\Python\3.12.8\x64\Lib\site-packages\matplotlib\backend_bases.py:1783: in new_manager
    return cls.manager_class.create_with_canvas(cls, figure, num)
C:\hostedtoolcache\windows\Python\3.12.8\x64\Lib\site-packages\matplotlib\backends\_backend_tk.py:507: in create_with_canvas
    window = tk.Tk(className="matplotlib")
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <tkinter.Tk object .>, screenName = None, baseName = '__main__'
className = 'matplotlib', useTk = True, sync = False, use = None

    def __init__(self, screenName=None, baseName=None, className='Tk',
                 useTk=True, sync=False, use=None):
        """Return a new top level widget on screen SCREENNAME. A new Tcl interpreter will
        be created. BASENAME will be used for the identification of the profile file (see
        readprofile).
        It is constructed from sys.argv[0] without extensions if None is given. CLASSNAME
        is the name of the widget class."""
        self.master = None
        self.children = {}
        self._tkloaded = False
        # to avoid recursions in the getattr code in case of failure, we
        # ensure that self.tk is always _something_.
        self.tk = None
        if baseName is None:
            import os
            baseName = os.path.basename(sys.argv[0])
            baseName, ext = os.path.splitext(baseName)
            if ext not in ('.py', '.pyc'):
                baseName = baseName + ext
        interactive = False
>       self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
E       _tkinter.TclError: Can't find a usable init.tcl in the following directories: 
E           {C:\hostedtoolcache\windows\Python\3.12.8\x64\tcl\tcl8.6}
E       
E       C:/hostedtoolcache/windows/Python/3.12.8/x64/tcl/tcl8.6/init.tcl: couldn't read file "C:/hostedtoolcache/windows/Python/3.12.8/x64/tcl/tcl8.6/init.tcl": No error
E       couldn't read file "C:/hostedtoolcache/windows/Python/3.12.8/x64/tcl/tcl8.6/init.tcl": No error
E           while executing
E       "source C:/hostedtoolcache/windows/Python/3.12.8/x64/tcl/tcl8.6/init.tcl"
E           ("uplevel" body line 1)
E           invoked from within
E       "uplevel #0 [list source $tclfile]"
E       
E       
E       This probably means that Tcl wasn't installed properly.