[build_debian.sh] Configure sshd to listen for IPv6 connections (#7719)

#### Why I did it

To allow SSH connections from IPv6 addresses

Resolves #7668

#### How I did it

In build_debian.sh, modify sshd_config file so as to enable listening for IPv6 connections

Author: jleveque

build_debian.sh

@@ -305,9 +305,9 @@ set /files/etc/ssh/sshd_config/#comment[following-sibling::*[1][self::ClientAliv
 save
 quit
 EOF
-# Configure sshd to listen for v4 connections; disable listening for v6 connections
-sudo sed -i 's/^ListenAddress ::/#ListenAddress ::/' $FILESYSTEM_ROOT/etc/ssh/sshd_config
+# Configure sshd to listen for v4 and v6 connections
 sudo sed -i 's/^#ListenAddress 0.0.0.0/ListenAddress 0.0.0.0/' $FILESYSTEM_ROOT/etc/ssh/sshd_config
+sudo sed -i 's/^#ListenAddress ::/ListenAddress ::/' $FILESYSTEM_ROOT/etc/ssh/sshd_config
 
 ## Config sysctl
 sudo mkdir -p $FILESYSTEM_ROOT/var/core