completions/zsh: Fix incomplete input names

Input name with ':' in it were not suggested entirely.

 completions/zsh/_riverctl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/completions/zsh/_riverctl b/completions/zsh/_riverctl
index f4f5b69..6d2b3b3 100644
--- a/completions/zsh/_riverctl
+++ b/completions/zsh/_riverctl
@@ -103,7 +103,7 @@ _riverctl()
                     _arguments '1: :->name' '2: :->commands' ':: :->args'
 
                     case "$state" in
-                        name) _values 'inputs' $(riverctl list-inputs | grep -e '^[^[:space:]]') ;;
+                        name)  _alternative "arguments:args:($(riverctl list-inputs | grep -e '^[^[:space:]]'))" ;;
                         commands)
                             local -a input_subcommands
                             input_subcommands=(