v1.8.0

MLJModelInterface v1.8.0

Diff since v1.7.1

• Add ProbabilisticSet <: Supervised model type (#167)
• Add augment keyword option to doc_header (#168)

Merged pull requests:

• Probabilisitic set (#167) (@pat-alt)
• Add augment option to doc_header (#168) (@ablaom)
• For a 1.8 release (#169) (@ablaom)