Using widget="binary" for fields.Text result in a TypeError
Previously in account_payment_sepa we had a fields.Text that was rendered with a Text widget and a Binary widget.
In this case, a decode error occurs when the user set a file as the Binary widget will send bytes to the record and the Text widget expect a str.
We might want to use the same strategy we used for the HTML widget and guess the encoding when the Char widget receives bytes.