Fix #1423 - extname is deprecated
Fix #1423 - extname is deprecated

Glavin001/atom-beautify,prettydiff/atom-beautify,Glavin001/atom-beautify,prettydiff/atom-beautify,Glavin001/atom-beautify,Glavin001/atom-beautify,prettydiff/atom-beautify,Glavin001/atom-beautify,prettydiff/atom-beautify