Merge branch 'develop' of git.ispconfig.org:ispconfig/ispconfig3 into develop

.gitlab-ci.yml

helper_scripts/test_install_docker.sh

interface/lib/classes/plugin_backuplist.inc.php

interface/lib/classes/validate_dns.inc.php

interface/web/dns/form/dns_soa.tform.php

interface/web/dns/lib/lang/ar_dns_soa.lng

interface/web/dns/lib/lang/bg_dns_soa.lng

interface/web/dns/lib/lang/el_dns_soa.lng

interface/web/dns/lib/lang/en_dns_soa.lng

interface/web/dns/lib/lang/fi_dns_soa.lng

interface/web/dns/lib/lang/hu_dns_soa.lng

interface/web/dns/lib/lang/id_dns_soa.lng

interface/web/dns/lib/lang/ja_dns_soa.lng

interface/web/dns/lib/lang/nl_dns_soa.lng

interface/web/dns/lib/lang/pt_dns_soa.lng

interface/web/dns/lib/lang/ro_dns_soa.lng

interface/web/dns/lib/lang/se_dns_soa.lng

interface/web/dns/lib/lang/sk_dns_soa.lng

interface/web/sites/form/web_vhost_domain.tform.php

interface/web/sites/lib/lang/ar_web_vhost_domain.lng