Fix forgotten test update

tests/pretty_basic/TF_RUN

@@ -4,7 +4,7 @@
 . "$TF_DIR/include/tools.sh"
 
 . "$(shellfu-get path)" || tf_exit_error "failed to init shellfu"
-SHELLFU_PRETTY=plain
+PRETTY=plain
 shellfu import pretty   || tf_exit_error "failed to import pretty"
 
 tf_enum_subtests() {
@@ -62,7 +62,7 @@ tf_do_subtest() {
     local o_out="oracle/$ttype/$tfun.stdout"
     local o_err="oracle/$ttype/$tfun.stderr"
     local cmd
-    tf_debug "SHELLFU_PRETTY=$SHELLFU_PRETTY"
+    tf_debug "PRETTY=$PRETTY"
     case $tfun in
         debug)          cmd='debug foo' ;;
         debug_pipe)     cmd='debug_pipe foo'; t_in="test/$name.stdin" ;;