Null pointer exception on export download

[PhilippeVienne]

With gitlab.com the "Content-Disposition" is not given, it causes a null pointer here on line 112:
https://github.com/gitlab4j/gitlab4j-api/blob/master/src/main/java/org/gitlab4j/api/ImportExportApi.java#L111-L113

[gmessner]

@PhilippeVienne
This has been released in 4.11.8. Please verify and close when you have the time.

Thanks again for your contribution.

[PhilippeVienne]

@gmessner
Thanks, it works 😄