I have repaired a number of bodhrans with similar holes or small tears by gluing a small strip or circle strip of thin leather or natural vellum such as that used on banjos over the damaged area from the inside surface of the skin using an adhesive such as Copydex or similar (not cyanoacrylate which is too "brittle"). All the repaired bodhrans are still in active service as far as I am aware. I don't think the glue on its own will be sufficient.