Add Class for Select Fields

[rimmeh8]

Since Bootstrap 5 we need special CLasses for Select fields class="form-select" . In Powermail 10.6 i can only change Classes of all fields: " Framework classname(s) for fields e.g. "form-control"[plugin.tx_powermail.settings.styles.bootstrap.fieldClasses] "

Would be nice if you can add an Option fpr Select FIeld Classes.