Remove widget import from __init__ (#76)

Qt Dependent import at top level results in build fail on conda because
of absence of pyqt in the environment
conda-forge/staged-recipes#32036

Author: TimMonko

src/napari_metadata/__init__.py

@@ -3,6 +3,4 @@
 except ImportError:
     __version__ = 'unknown'
 
-from ._widget import MetadataWidget
-
-__all__ = ('MetadataWidget',)
+__all__ = ()