feat: cant pin if only pne env exists

cmd/pin.go

@@ -40,6 +40,11 @@ var pinCmd = &cobra.Command{
 			envs, err := utils.GetEnvironments(dbProject.ID)
 			utils.StopIfErr(err)
 
+			if len(envs) == 1 {
+				utils.ErrPrint("The current environment is already pinned.")
+				os.Exit(1)
+			}
+
 			form := huh.NewForm(
 				huh.NewGroup(
 					huh.NewSelect[string]().