fix: [stix2 import] Fixed pattern parsing
fix: [stix2 import] Fixed pattern parsing

- Stripping patterns to avoid issue with space
  characters at the beginning or at the end of the
  patterns

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