Minor update to the COI database of Metaxa2

A few days ago, my attention was turned to a duplicate in the COI database bundled with Metaxa2 2.2. While this duplicate sequence should not cause any troubles for Metaxa2 itself, it has created issues for people using the database itself together with, e.g., QIIME. Therefore, I have today issued a very very minor update to the Metaxa2 2.2 package as well as the entry in the Metaxa2 Database Repository, removing the duplicate sequence. I deemed that this was not significant enough to issue a new version, particularly as no code was changed and it did not cause issues for the software itself, so the version will stay at 2.2 for the time being. Happy barcoding!