seurat::key in RunHarmony results in an error

[DivyaRavichandar]

Running the RunHarmony(seuratobject) with seurat 4.0.3 results in the following error

  no applicable method for 'Key' applied to an object of class "character"```

The issue seems to stem from this one line of code in RunHarmony.R that was recently added
`reduction.key <- Seurat::Key(reduction.save, quiet = TRUE)`

Is this edit backward compatible with older Seurat versions?