Address scipy deprecation warnings

[tbirdso]

Several deprecation warnings appear in test logs. Relevant scipy.ndimage.filters filters should be replaced with their counterparts from scipy.ndimage.

test/test_multiscale_spatial_image.py::test_gaussian_isotropic_scale_factors
  Please use `convolve` from the `scipy.ndimage` namespace, the `scipy.ndimage.filters` namespace is deprecated.

test/test_multiscale_spatial_image.py::test_gaussian_isotropic_scale_factors
  Please use `correlate` from the `scipy.ndimage` namespace, the `scipy.ndimage.filters` namespace is deprecated.

test/test_multiscale_spatial_image.py::test_gaussian_isotropic_scale_factors
  Please use `laplace` from the `scipy.ndimage` namespace, the `scipy.ndimage.filters` namespace is deprecated.

test/test_multiscale_spatial_image.py::test_gaussian_isotropic_scale_factors
  Please use `prewitt` from the `scipy.ndimage` namespace, the `scipy.ndimage.filters` namespace is deprecated.

test/test_multiscale_spatial_image.py::test_gaussian_isotropic_scale_factors
  Please use `sobel` from the `scipy.ndimage` namespace, the `scipy.ndimage.filters` namespace is deprecated.

test/test_multiscale_spatial_image.py: 13 warnings
  Please use `gaussian_filter` from the `scipy.ndimage` namespace, the `scipy.ndimage.filters` namespace is deprecated.

test/test_multiscale_spatial_image.py::test_gaussian_isotropic_scale_factors
  Please use `gaussian_gradient_magnitude` from the `scipy.ndimage` namespace, the `scipy.ndimage.filters` namespace is deprecated.

test/test_multiscale_spatial_image.py::test_gaussian_isotropic_scale_factors
  Please use `gaussian_laplace` from the `scipy.ndimage` namespace, the `scipy.ndimage.filters` namespace is deprecated.

test/test_multiscale_spatial_image.py::test_gaussian_isotropic_scale_factors
  Please use `generic_filter` from the `scipy.ndimage` namespace, the `scipy.ndimage.filters` namespace is deprecated.

test/test_multiscale_spatial_image.py::test_gaussian_isotropic_scale_factors
  Please use `minimum_filter` from the `scipy.ndimage` namespace, the `scipy.ndimage.filters` namespace is deprecated.

test/test_multiscale_spatial_image.py::test_gaussian_isotropic_scale_factors
  Please use `median_filter` from the `scipy.ndimage` namespace, the `scipy.ndimage.filters` namespace is deprecated.

test/test_multiscale_spatial_image.py::test_gaussian_isotropic_scale_factors
  Please use `maximum_filter` from the `scipy.ndimage` namespace, the `scipy.ndimage.filters` namespace is deprecated.

test/test_multiscale_spatial_image.py::test_gaussian_isotropic_scale_factors
  Please use `rank_filter` from the `scipy.ndimage` namespace, the `scipy.ndimage.filters` namespace is deprecated.

test/test_multiscale_spatial_image.py::test_gaussian_isotropic_scale_factors
  Please use `percentile_filter` from the `scipy.ndimage` namespace, the `scipy.ndimage.filters` namespace is deprecated.

test/test_multiscale_spatial_image.py::test_gaussian_isotropic_scale_factors
  Please use `uniform_filter` from the `scipy.ndimage` namespace, the `scipy.ndimage.filters` namespace is deprecated.

[thewtex]

Addressed by @GenevieveBuckley via dask/dask-image#269