Bugfix: call node print function instead of built-in print function (#188)

When printing the AST to a string using the SprintSyntaxTree function, I was seeing pointer addresses being printed to stdout. Upon looking at the code, I found that in the `printFunc` function that writes the AST to a `io.Writer`, the recursive call is incorrectly calling the built-in `print` function instead of `printFunc`.

Author: khilangudka

tree/peg.go.tmpl

@@ -62,7 +62,7 @@ func (n *node[U]) print(w io.Writer, pretty bool, buffer string) {
 				fmt.Fprintf(w, "\x1B[36m%v\x1B[m %v\n", rule, quote)
 			}
 			if n.up != nil {
-				print(n.up, depth+1)
+				printFunc(n.up, depth+1)
 			}
 			n = n.next
 		}