bug: fortran file extension is wrong

base on documentation in [fortran wiki](https://fortranwiki.org/fortran/show/File+extensions), common fortran file extensions are *.f, *.*for and *.f90 but in [configuration table](https://github.com/nvim-tree/nvim-web-devicons/blob/467d135bbefa6fbe8380c8b6498228f8b21244a6/lua/nvim-web-devicons.lua#L1610) f# has been set.
