.idea: remove duplicate killbill-plugin-api-invoice entry
.idea: remove duplicate killbill-plugin-api-invoice entry

Signed-off-by: Pierre-Alexandre Meyer <ff019a5748a52b5641624af88a54a2f0e46a9fb5@mouraf.org>

killbill/killbill-plugin-api,killbill/killbill-plugin-api