CombineExt 1.6.0

• Add retry(when:) (Thanks @danielt1263)
• Add enumerated() (Thanks @mihai8804858)
• Add map(to:) (Thanks @danhalliday)
• Fix a memory leak in withLatestFrom (Thanks @bharath2020)
• Fix an issue with share(replay:) (Thanks @jabeattie @mRs-)