Use year range in the license file
Use year range in the license file

As discussed in https://github.com/stylelint/stylelint/pull/730

gaidarenko/stylelint,gaidarenko/stylelint,gaidarenko/stylelint,hudochenkov/stylelint,gucong3000/stylelint,hudochenkov/stylelint,hudochenkov/stylelint,evilebottnawi/stylelint,heatwaveo8/stylelint,stylelint/stylelint,stylelint/stylelint,heatwaveo8/stylelint,stylelint/stylelint,m-allanson/stylelint,stylelint/stylelint,heatwaveo8/stylelint,gucong3000/stylelint,gucong3000/stylelint,evilebottnawi/stylelint