Bump xstream from 1.4.14 to 1.4.15
Bump xstream from 1.4.14 to 1.4.15

Bumps [xstream](https://github.com/x-stream/xstream) from 1.4.14 to 1.4.15.
- [Release notes](https://github.com/x-stream/xstream/releases)
- [Commits](https://github.com/x-stream/xstream/commits)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
daniel-beck/jenkins,damianszczepanik/jenkins,pjanouse/jenkins,ikedam/jenkins,damianszczepanik/jenkins,DanielWeber/jenkins,DanielWeber/jenkins,ikedam/jenkins,ikedam/jenkins,v1v/jenkins,rsandell/jenkins,ikedam/jenkins,jenkinsci/jenkins,daniel-beck/jenkins,viqueen/jenkins,jenkinsci/jenkins,jenkinsci/jenkins,viqueen/jenkins,MarkEWaite/jenkins,rsandell/jenkins,pjanouse/jenkins,MarkEWaite/jenkins,damianszczepanik/jenkins,v1v/jenkins,viqueen/jenkins,damianszczepanik/jenkins,DanielWeber/jenkins,MarkEWaite/jenkins,v1v/jenkins,jenkinsci/jenkins,v1v/jenkins,pjanouse/jenkins,damianszczepanik/jenkins,damianszczepanik/jenkins,daniel-beck/jenkins,rsandell/jenkins,ikedam/jenkins,DanielWeber/jenkins,daniel-beck/jenkins,rsandell/jenkins,DanielWeber/jenkins,viqueen/jenkins,rsandell/jenkins,MarkEWaite/jenkins,MarkEWaite/jenkins,v1v/jenkins,daniel-beck/jenkins,MarkEWaite/jenkins,ikedam/jenkins,ikedam/jenkins,viqueen/jenkins,jenkinsci/jenkins,damianszczepanik/jenkins,pjanouse/jenkins,rsandell/jenkins,pjanouse/jenkins,pjanouse/jenkins,MarkEWaite/jenkins,rsandell/jenkins,daniel-beck/jenkins,viqueen/jenkins,ikedam/jenkins,jenkinsci/jenkins,jenkinsci/jenkins,damianszczepanik/jenkins,rsandell/jenkins,daniel-beck/jenkins,MarkEWaite/jenkins,DanielWeber/jenkins,v1v/jenkins,viqueen/jenkins,daniel-beck/jenkins,jenkinsci/jenkins,DanielWeber/jenkins,pjanouse/jenkins,v1v/jenkins