fix shallow-backup completion

- fix wrong syntax
- simplify code

src/_shallow-backup

@@ -38,33 +38,29 @@
 #
 # ------------------------------------------------------------------------------
 
-_shallow-backup() {
-  _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' \
-    '--backup-all[Full back up]' \
-    '--backup-configs[Back up app config files]' \
-    '--backup-dots[Back up dotfiles]' \
-    '--backup-fonts[Back up installed fonts]' \
-    '--backup-packages[Back up package libraries]' \
-    '--delete-config[Delete config file]' \
-    '--destroy-backup[Delete backup directory]' \
-    '--dry-run[Do not backup or reinstall any files, just give verbose output]' \
-    '--new-path[Input a new back up directory path]:PATH:_files -/' \
-    '--no-new-backup-path-prompt[Skip setting new back up directory path prompt]' \
-    '--no-splash[Do not display splash screen]' \
-    '--reinstall-all[Full reinstallation]' \
-    '--reinstall-configs[Reinstall configs]' \
-    '--reinstall-dots[Reinstall dotfiles and dotfolders]' \
-    '--reinstall-fonts[Reinstall fonts]' \
-    '--reinstall-packages[Reinstall packages]' \
-    '--remote[Set remote URL for the git repo]':url \
-    '--edit[Open config file in $EDITOR]' \
-    '--show[Display config file]'
-}
-
-_shallow-backup
+_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' \
+  '--backup-all[Full back up]' \
+  '--backup-configs[Back up app config files]' \
+  '--backup-dots[Back up dotfiles]' \
+  '--backup-fonts[Back up installed fonts]' \
+  '--backup-packages[Back up package libraries]' \
+  '--delete-config[Delete config file]' \
+  '--destroy-backup[Delete backup directory]' \
+  '--dry-run[Do not backup or reinstall any files, just give verbose output]' \
+  '--new-path[Input a new back up directory path]:PATH:_files -/' \
+  '--no-new-backup-path-prompt[Skip setting new back up directory path prompt]' \
+  '--no-splash[Do not display splash screen]' \
+  '--reinstall-all[Full reinstallation]' \
+  '--reinstall-configs[Reinstall configs]' \
+  '--reinstall-dots[Reinstall dotfiles and dotfolders]' \
+  '--reinstall-fonts[Reinstall fonts]' \
+  '--reinstall-packages[Reinstall packages]' \
+  '--remote[Set remote URL for the git repo]:url' \
+  '--edit[Open config file in $EDITOR]' \
+  '--show[Display config file]'
 
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 # mode: Shell-Script