Merge tag '2.1.3' into develop

Tagging version 2.1.3 2.1.3
[BUGFIX] BE modul: Fatal error

$field can be null now. Added a basicly behavior test for the backend module in powermail.

related: #62048
Manual update, new version 2.1.4
Manual update, new version 2.1.4
Merge remote-tracking branch 'origin/develop' into develop
Merge branch 'release/2.1.4'