fix version

Author: kmuehlbauer

wradlib_data/__init__.py

@@ -6,7 +6,7 @@
 from .dataset import DATASETS, locate
 
 try:
-    _version__ = _importlib_metadata.version("wradlib-data")
+    __version__ = _importlib_metadata.version("wradlib-data")
 except _importlib_metadata.PackageNotFoundError:  # pragma: no cover
     # package is not installed
     __version__ = 'unknown'  # pragma: no cover