Allow building with ghc-prim-0.7.*
Allow building with ghc-prim-0.7.*

This is needed for
[GHC#18279](https://gitlab.haskell.org/ghc/ghc/issues/18279), which
seeks to bump `ghc-prim`'s version number to 0.7.0.0 in order to
accommodate `GHC.Tuple.Unit` being renamed to `GHC.Tuple.Solo`. Since
`text` does not use `GHC.Tuple.Unit`, it is safe to simply bump
`text`'s upper version bounds on `ghc-prim`.

bgamari/text,bos/text,bos/text,bgamari/text,bos/text,bos/text,bgamari/text,bgamari/text