Add upstream to github command

[holly-cummins]

Run git checkout -b alpha-10309392019
Switched to a new branch 'alpha-10309392019'
[alpha-10309392019 8ac5628] Automatic alphabetisation
 1 file changed, 28 insertions(+), 31 deletions(-)
fatal: The current branch alpha-10309392019 has no upstream branch.
To push the current branch and set the remote as upstream, use

    git push --set-upstream origin alpha-10309392019

To have this happen automatically for branches without a tracking
upstream, see 'push.autoSetupRemote' in 'git help config'.

😢

[github-actions]

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