[processing] nviz is not available in GRASS 7 (fix #17145)

Author: alexbruy

python/plugins/processing/algs/grass7/Grass7AlgorithmProvider.py

@@ -33,7 +33,6 @@
 from .Grass7Utils import Grass7Utils
 from .Grass7Algorithm import Grass7Algorithm
 from processing.tools.system import isWindows, isMac
-from .nviz7 import nviz7
 
 pluginPath = os.path.normpath(os.path.join(
     os.path.split(os.path.dirname(__file__))[0], os.pardir))