Disable track_overflow in PointSourceResponse

[hiyoneda]

Currently, track_overflow is set to True when generating an instance of PointSourceResponse. I think that track_overflow should always be False because the under/overflow bins will not be used in the response files.

Probably, we can simply add these lines in PointSourceResponse:

   def __init__(self, *args, **kwargs):
        """
        Initialize a PointSourceResponse object.
        """
        # Not to track the under/overflow bins
        kwargs['track_overflow'] = False

        super().__init__(*args, **kwargs)

But when I tried this change and tested it, it caused errors in the unit test.

________________________________________________________ test_inject_point_source_saving ________________________________________________________

    def test_inject_point_source_saving():

        # defind the response and orientation
        response_path = test_data.path / "test_precomputed_response.h5"

        # powerlaw model
        index = -2.2
        K = 17 / u.cm / u.cm / u.s / u.keV
        piv = 1 * u.keV
        spectrum = Powerlaw()
        spectrum.index.value = index
        spectrum.K.value = K.value
        spectrum.piv.value= piv.value
        spectrum.K.unit = K.unit
        spectrum.piv.unit = piv.unit

        # Define an injector by the response
        injector = SourceInjector(response_path = response_path, response_frame = "galactic")

        # Define the coordinate of the point source
        source_coord = SkyCoord(l = 50, b = -45, frame = "galactic", unit = "deg")

        # Get the data of the injected source
>       injected_crab_signal = injector.inject_point_source(spectrum = spectrum, coordinate = source_coord,
                                                            source_name = "point_source",
                                                            make_spectrum_plot = False, data_save_path = Path("./galactic_rsp.h5"),
                                                            project_axes = "Em")

tests/source_injector/test_source_injector.py:112:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
cosipy/source_injector/source_injector.py:136: in inject_point_source
    psr = SourceInjector.get_psr_in_galactic(coordinate = coordinate, response_path = self.response_path, spectrum = spectrum)
cosipy/source_injector/source_injector.py:81: in get_psr_in_galactic
    psr = PointSourceResponse(axes[1:], f['hist/contents'][pix+1], unit = f['hist'].attrs['unit'])
cosipy/response/PointSourceResponse.py:41: in __init__
    super().__init__(*args, **kwargs)