readd macos support

autoload/coc/pses.vim

@@ -1,12 +1,18 @@
 let s:root           = expand('<sfile>:h:h:h')
 let s:is_win         = has('win32') || has('win64')
+let s:is_mac = !s:is_windows && !s:is_cygwin
+      \ && (has('mac') || has('macunix') || has('gui_macvim') ||
+      \   (!isdirectory('/proc') && executable('sw_vers')))
 let s:is_vim         = !has('nvim')
 let s:install_script = s:root.'/'.(s:is_win ? 'install.cmd' : 'install.ps1')
 
+if(s:is_mac)
+    let s:install_script = 'pwsh '.s:install_script
+endif
+
 function! coc#pses#install()
     let cwd = getcwd()
     exe 'lcd '.s:root
     exe '!'.s:install_script
     exe 'lcd '.cwd
 endfunction
-