Update install.sh

install.sh

@@ -56,7 +56,7 @@ echo "roundcube-core roundcube/mysql/app-pass password" | debconf-set-selections
 echo "roundcube-core roundcube/reconfigure-webserver select apache2" | debconf-set-selections
 
 echo -n "Adding repository key..."
-wget -qO- http://mirror.mythic-beasts.com/mythic/support@mythic-beasts.com.gpg.key | apt-key add -
+wget -qO- https://mirror.mythic-beasts.com/mythic/support@mythic-beasts.com.gpg.key | apt-key add -
 
 if [ "$(find /etc/apt/sources.list.d/ -mindepth 1 -maxdepth 1 -type f -name 'sympl_*.list' | wc -l )" != "0" ]; then
   echo -n "Removing previous Sympl repo..."