[BUGFIX] Fix BS change of translationFile inclusions in TYPO3 10 but keep the...

[BUGFIX] Fix BS change of translationFile inclusions in TYPO3 10 but keep the old setting for TYPO3 9 compatibility

Configuration/Yaml/Forms/FinisherSetupBE.yaml

@@ -7,6 +7,9 @@ TYPO3:
             translationFile:
               10: 'EXT:form/Resources/Private/Language/Database.xlf'
               20: 'EXT:sg_mail/Resources/Private/Language/Database.xlf'
+            translationFiles:
+              10: 'EXT:form/Resources/Private/Language/Database.xlf'
+              20: 'EXT:sg_mail/Resources/Private/Language/Database.xlf'
           finishersDefinition:
             # TODO deprecated finisher (migration wizard required)
             MailToSenderFinisher:
@@ -335,3 +338,5 @@ TYPO3:
                 translation:
                   translationFile:
                     90: 'EXT:project_theme/Resources/Private/Language/forms.xlf'
+                  translationFiles:
+                    90: 'EXT:project_theme/Resources/Private/Language/forms.xlf'