For filter submodule, explicitly set warning registry location

skimage/filter/__init__.py

@@ -1,9 +1,12 @@
 from skimage._shared.utils import skimage_deprecation
-from warnings import warn
-warn(skimage_deprecation('The `skimage.filter` module has been renamed to '
-                         '`skimage.filters`.  This placeholder module '
-                         'will be removed in v0.13.'))
-del warn
+from warnings import warn_explicit
+__warningregistry__ = {}
+warn_explicit(skimage_deprecation('The `skimage.filter` module has been renamed to '
+                                  '`skimage.filters`.  This placeholder module '
+                                  'will be removed in v0.13.'), category=None,
+                                  filename=__file__, lineno=4,
+                                  registry=__warningregistry__)
+del warn_explicit
 del skimage_deprecation
 
 from ..filters import *