cleanups for Auth::validate_password commit

one for testing to work again
and one to remove MD5 dependency in Plugin.pm

lib/Qpsmtpd/Plugin.pm

@@ -4,7 +4,6 @@ use strict;
 use warnings;
 
 use Qpsmtpd::Constants;
-use Digest::HMAC_MD5 qw(hmac_md5_hex);
 
 # more or less in the order they will fire
 our @hooks = qw(

t/Test/Qpsmtpd.pm

@@ -1,6 +1,7 @@
 package Test::Qpsmtpd;
 use strict;
 use lib 't';
+use lib 'lib';
 use Carp qw(croak);
 use base qw(Qpsmtpd::SMTP);
 use Test::More;