Update xeus-cpp to 0.7.1 for release#344

mcbarton wants to merge 1 commit intocompiler-research:maincompiler-research/xeus-cpp:mainfrom

mcbarton:Set-version-to-0.7.1-for-releasemcbarton/xeus-cpp:Set-version-to-0.7.1-for-releaseCopy head branch name to clipboard