fix threshold_yen import

skimage/filter/__init__.py

@@ -9,7 +9,7 @@ from ._denoise import denoise_tv_chambolle
 from ._denoise_cy import denoise_bilateral, denoise_tv_bregman
 from ._rank_order import rank_order
 from ._gabor import gabor_kernel, gabor_filter
-from .thresholding import threshold_otsu, threshold_adaptive
+from .thresholding import threshold_adaptive, threshold_otsu, threshold_yen
 from . import rank
 
 
@@ -37,6 +37,7 @@ __all__ = ['inverse',
            'rank_order',
            'gabor_kernel',
            'gabor_filter',
-           'threshold_otsu',
            'threshold_adaptive',
+           'threshold_otsu',
+           'threshold_yen',
            'rank']