merge-pr: add reviewer info to commit message
merge-pr: add reviewer info to commit message

This produces a commit message like
~~~
Merge PR #9250: coqchk: fix check for kelim with functors

Reviewed-by: ppedrot
Ack-by: mattam92
~~~

gares/coq,SkySkimmer/coq,coq/coq,gares/coq,coq/coq,silene/coq,ppedrot/coq,ejgallego/coq,ppedrot/coq,Zimmi48/coq,ejgallego/coq,maximedenes/coq,Zimmi48/coq,coq/coq,gares/coq,Matafou/coq,SkySkimmer/coq,silene/coq,maximedenes/coq,Matafou/coq,maximedenes/coq,ppedrot/coq,Zimmi48/coq,ejgallego/coq,ppedrot/coq,Matafou/coq,SkySkimmer/coq,silene/coq,coq/coq,JasonGross/coq,maximedenes/coq,gares/coq,ejgallego/coq,JasonGross/coq,maximedenes/coq,gares/coq,JasonGross/coq,ppedrot/coq,JasonGross/coq,Zimmi48/coq,SkySkimmer/coq