Bug 28386: Add sponsors to .mailmap

Bug 28386: Add sponsors to .mailmap

They were in dev_map.yaml, we are cheating with the <sponsor> email but
it seems to work fine in my tests

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit d102651d1b6e9bb7c20835f8e4ca4645926f6ec5)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
(cherry picked from commit a39fbc135912bdcdeded6edb9e3596be61321524)
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>