common : add -m to bash completion for --model [no ci] (#15591)

This commit updates the bash completion script to include the -m
short option for the --model argument.

The motivation for this is that currently tab completion only works the
full --model option, and it is nice to have it work for the short option
as well.

common/arg.cpp

@@ -1106,7 +1106,7 @@ static void common_params_print_completion(common_params_context & ctx_arg) {
     printf("\"\n\n");
 
     printf("    case \"$prev\" in\n");
-    printf("        --model)\n");
+    printf("        --model|-m)\n");
     printf("            COMPREPLY=( $(compgen -f -X '!*.gguf' -- \"$cur\") $(compgen -d -- \"$cur\") )\n");
     printf("            return 0\n");
     printf("            ;;\n");