Add support for TEXT_DATETIME

[CGenie]

For my DB I'm getting:

┌ Warning: Unsupported SQLite declared type TEXT_DATETIME, falling back to String type
└ @ SQLite ~/.julia/packages/SQLite/aDggE/src/SQLite.jl:416

I guess TEXT_DATETIME should be supported by Julia though I can't find it officially mentioned in the documentation:
https://www.sqlite.org/datatype3.html

[quinnj]

Yeah, we're talking about removing the warning since we can't possible cover all possible types since sqlite allows you to put "anything" as the column type (ref #279 )