Intermittent tcl/Tkinter installation failure leading to matplotlib test failure for Windows runner

[DanielYang59]

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It seems GitHub Windows runner sometimes failed to install tk backend which leads to matplotlib error, do note however the agg backend should be used for non-interactive tests:

https://matplotlib.org/stable/users/explain/figure/backends.html
The last, Agg, is a non-interactive backend that can only write to files. It is used on Linux, if Matplotlib cannot connect to either an X display or a Wayland display.

Example error log:

src\pymatgen\util\plotting.py:61: in pretty_plot
    plt.figure(figsize=(width, height), facecolor="w", dpi=dpi)
C:\Users\runneradmin\micromamba\envs\pmg\lib\site-packages\matplotlib\pyplot.py:1027: in figure
    manager = new_figure_manager(
C:\Users\runneradmin\micromamba\envs\pmg\lib\site-packages\matplotlib\pyplot.py:550: in new_figure_manager
    return _get_backend_mod().new_figure_manager(*args, **kwargs)
C:\Users\runneradmin\micromamba\envs\pmg\lib\site-packages\matplotlib\backend_bases.py:3507: in new_figure_manager
    return cls.new_figure_manager_given_figure(num, fig)
C:\Users\runneradmin\micromamba\envs\pmg\lib\site-packages\matplotlib\backend_bases.py:3512: in new_figure_manager_given_figure
    return cls.FigureCanvas.new_manager(figure, num)
C:\Users\runneradmin\micromamba\envs\pmg\lib\site-packages\matplotlib\backend_bases.py:1797: in new_manager
    return cls.manager_class.create_with_canvas(cls, figure, num)
C:\Users\runneradmin\micromamba\envs\pmg\lib\site-packages\matplotlib\backends\_backend_tk.py:483: in create_with_canvas
    window = tk.Tk(className="matplotlib")
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <tkinter.Tk object .>, screenName = None, baseName = 'pytest'
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: invalid command name "tcl_findLibrary"

Another error:

>       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:/Users/runneradmin/micromamba/envs/pmg/Library/lib/tcl8.6 C:/Users/runneradmin/micromamba/envs/lib/tcl8.6 C:/Users/runneradmin/micromamba/lib/tcl8.6 C:/Users/runneradmin/micromamba/envs/library C:/Users/runneradmin/micromamba/library C:/Users/runneradmin/micromamba/tcl8.6.13/library C:/Users/runneradmin/tcl8.6.13/library
E       
E       C:/Users/runneradmin/micromamba/envs/pmg/Library/lib/tcl8.6/init.tcl: couldn't read file "C:/Users/runneradmin/micromamba/envs/pmg/Library/lib/tcl8.6/init.tcl": No error
E       couldn't read file "C:/Users/runneradmin/micromamba/envs/pmg/Library/lib/tcl8.6/init.tcl": No error
E           while executing
E       "source C:/Users/runneradmin/micromamba/envs/pmg/Library/lib/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.

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