feat: update for Flix version 0.45.0

src/Parser.flix

@@ -224,7 +224,7 @@ mod Parser {
     /// Returns `chars` as a string.
     ///
     pub def stringify(chars: m[Char]): String with Foldable[m] = region r {
-        let sb = StringBuilder.new(r);
+        let sb = StringBuilder.empty(r);
         let ap = sb |> flip(StringBuilder.append!);
         Foldable.forEach(ap, chars);
         StringBuilder.toString(sb)