Here is an example solution. It may not be the best but at least it is correct. You can take this and modify it further as your requirements change.

use strict;
use warnings;
use utf8;

use Test::More tests => 1;

my $in = <<EOT;
This is a test posting.
•   Hello there!
•   How are you?
•   Very well I hope!
This is the end of the posting.
EOT

my $want = '<p>This is a test posting.<ul><li>Hello there!</li><li>How
+ are you?</li><li>Very well I hope!</li></ul>This is the end of the p
+osting.</p>';

my $have = '<p>';
my $inlist = 0;

for (split /\n/, $in) {
    if (s/•\s*/<li>/) {
        $_ .= '</li>';
        $_ = '<ul>' . $_ unless $inlist;
        $inlist = 1;
    } elsif ($inlist) {
        $_ = '</ul>' . $_;
        $inlist = 0;
    }
    $have .= $_;
}
$have .= '</p>';

is $have, $want;
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