Fix deprecation of getproperty(::Pairs, s) in Julia 1.7 

As of Julia v1.7 JuliaLang/julia#39448 deprecated `getproperty(::Pairs, s)`.  This currently causes a warning and should be updated:

```
┌ Warning: use values(kwargs) and keys(kwargs) instead of kwargs.data and kwargs.itr
│   caller = #transform#3 at TableOperations.jl:39 [inlined]
└ @ Core ~/.julia/packages/TableOperations/d5QI0/src/TableOperations.jl:39
```
