Changing back to [[]] for feature-level metadata

[Gesmira]

SeuratObject is going back to using the double bracket [[]] for feature-level metadata and using single brackets [] for accessing layer data. This switch caused the below code to fail.

> pbmc.atac <- LoadData("pbmcMultiome", "pbmc.atac")
> pbmc.atac <- subset(pbmc.atac, seurat_annotations != 'filtered')
Error in `LayerData<-`(object = `*tmp*`, layer = i, ..., value = value) : 
  'value' must be a 'matrix' or 'dgCMatrix' in v3 Assays, not a 'data.frame'

I just removed the specific check for SeuratObject version as now the previous code will work normally.

[timoast]

Thanks!