Build failure with ghc-8.10.1

```
Data/Text/Format/Functions.hs:16:7: error:
    Ambiguous occurrence ‘<>’
    It could refer to
       either ‘GHC.Base.<>’,
              imported from ‘GHC.Base’ at Data/Text/Format/Functions.hs:22:1-15
           or ‘Data.Text.Format.Functions.<>’,
              defined at Data/Text/Format/Functions.hs:32:1
   |
16 |       (<>)
   |       ^^^^
```