fix shallow-backup completion

- fix wrong syntax
- simplify code

src/_shallow-backup

@@ -38,8 +38,7 @@
 #
 # ------------------------------------------------------------------------------
 
-_shallow-backup() {
-  _arguments \
+_arguments \
   '(- 1 *)'{-h,--help}'[Show help and exit]' \
   '(- 1 *)'{-v,--version}'[Print version]' \
   '--add-dot[Add a dotfile or dotfolder to config by path]:PATH:_files' \
@@ -59,12 +58,9 @@ _shallow-backup() {
   '--reinstall-dots[Reinstall dotfiles and dotfolders]' \
   '--reinstall-fonts[Reinstall fonts]' \
   '--reinstall-packages[Reinstall packages]' \
-    '--remote[Set remote URL for the git repo]':url \
+  '--remote[Set remote URL for the git repo]:url' \
   '--edit[Open config file in $EDITOR]' \
   '--show[Display config file]'
-}
-
-_shallow-backup
 
 # Local Variables:
 # mode: Shell-Script