Fix #23 stop assigning list from list.append

[VDFaller]

Summary of Changes

Fixes #23
Change {% set columns = columns.append(...) %} to {% do columns.append(...) %}

Why Do We Need These Changes

Otherwise dbt-fusion won't work with dbt-expectations. They said they don't plan on fixing dbt-labs/dbt-fusion#484, which seems reasonable.

Reviewers

@tpoll @gusvargas

[owenprough-sift]

@GuruM (since you've reviewed/merged PRs in this repo recently): what is the process for getting review on community-submitted PRs?

[VDFaller]

Awesome! Thanks @GuruM, now we can go back to the maintained version.