v3.7.4

Changed

• Replace with a value of a different length searches the text once instead of twice.
• AppendFormat searches for placeholders vectorized and reads single-digit indices like {0} without int.TryParse.
• Append(bool) writes without pinning or bounds checks, Append(Rune) and Insert(int, Rune) skip the stack buffer for BMP runes, and string values in AppendJoin, AppendFormat and Concat skip the ISpanFormattable check.