fix:space after cd

Error after FloatermNew in window. it showed '''Error detected while processing function floaterm#run[7]..floaterm#new[36]..floaterm#terminal#open[22]..floaterm#path#chdir:
line    2:
E492: Not an editor command: cdC:\Users\xxx'''

autoload/floaterm/path.vim

@@ -137,5 +137,5 @@ endfunction
 
 function! floaterm#path#chdir(path) abort
   let l:cd = { 0: 'cd', 1: 'lcd', 2: 'tcd' }[haslocaldir()]
-  silent execute l:cd . fnameescape(a:path)
+  silent execute l:cd . ' ' . fnameescape(a:path)
 endfunction