Square brackets for compound sort key syntax in DBT

[patdough5]

While working on creating a small DBT file, the discussion of whether or not to use () or [] came up when referring to compound keys. @tjengel pointed out that DBT docs refer to using []. Documentation can be found here

[atharvai]

sort accepts a list of sort keys,

A list in python is denoted using [] not () which is a tuple. Hopefully this isn't a point of contention.

[patdough5]

Typo, my bad Atharva. It is more for consistency and following DBTs docs.

[tmastny]

If the docs say we should use lists instead of tuples, that's what we should do. I think it is just a coincidence that tuples work, likely because they both implement the iterator methods.