Fix vimscript9 after patch 8.2-4053

Author: mark2185

autoload/alternator9.vim

@@ -23,7 +23,7 @@ def FindFiles( filename: string ): list< string >
     endif
 enddef
 
-export def alternator9#alternate(): void
+export def Alternate(): void
     if &modified && !&hidden
         echo "No write since last change, cannot alternate!"
         return

plugin/alternator.vim

@@ -10,8 +10,8 @@ let g:alternator_header_extensions = get( g:, 'alternator_header_extensions', [
 let g:alternator_source_extensions = get( g:, 'alternator_source_extensions', [ '.c', '.cpp',                ] )
 let g:alternator_blacklist_folders = get( g:, 'alternator_blacklist_folders', [ 'node_modules', '.git'       ] )
 
-if has('patch-8.2.3401')
-    command! Alternate call alternator9#alternate()
+if has('patch-8.2.4053')
+    command! Alternate call alternator9#Alternate()
 else
     command! Alternate call alternator#alternate()
 endif