message: fix: correctly serialize insertions in ACGT alphabet
diff: @@ -81,7 +81,7 @@ namespace Nextclade {
  auto j = json::object();
  j.emplace("pos", ins.pos);
  j.emplace("length", ins.length);
  - j.emplace("ins", ins.ins);
  + j.emplace("ins", toString(ins.ins));
  return j;
  }
  