fix: [stix2 export] Fixed first_seen/last_seen field parsing
fix: [stix2 export] Fixed first_seen/last_seen field parsing

SteveClement/MISP,MISP/MISP,MISP/MISP,SteveClement/MISP,MISP/MISP,SteveClement/MISP,SteveClement/MISP,MISP/MISP,SteveClement/MISP,MISP/MISP