bcrypt < 5 always truncated overlong passwords for us, since version 5
we need to do that on our own or hope our password library does it for
us.
In order to support both passlib and libpass with bcrypt >= 5 we simply
truncate if needed so it does not matter which of the two libraries is
used.
Closes: #1896
Signed-off-by: Henning Schild <henning@hennsch.de>