cast List[BigDecimal] cause ElemWitness[scala.math.BigDecimal]] not found

[markstock7]

I try to define a column[List[BigDecimal] using the Solution https://github.com/tminglei/slick-pg/issues/244.

But it throw a new error: not found ElemWitness[scala.math.BigDecimal]]

[tminglei]

@markstock7 I added a test case for column[List[scala.math.BigDecimal], it looks ok. pls see above commit for details.