Update .gitlab-ci.yml

Add CHANGELOG.de.md to Package
6 jobs for Fireflyer47-master-patch-41250 in 11 minutes and 18 seconds (queued for 1 second)
Name Stage Failure
package Package
$ cp -r l10n/ spgverein/
$ cp -r lib/ spgverein/
$ cp -r templates/ spgverein/
$ cp -r vendor/ spgverein/
$ cp -r CHANGELOG.md spgverein/
$ cp -r CHANGELOG.de.md spgverein/
cp: can't stat 'CHANGELOG.de.md': No such file or directory
Cleaning up file based variables
ERROR: Job failed: exit code 1