[BUG] Unwanted uppercase conversion in staging macro

[dcallananILMN]

Describe the bug When columns from the source model and/or derived columns have mixed casing the hashed_columns and columns_to_select CTEs are incorrect as they update all column names to uppercase.

Versions

dbt: 1.1.0 dbtvault: 0.8.3

To Reproduce Steps to reproduce the behavior:

1. Have a source model with pascal/camel case column names,
2. Add a derived column with pascal/camel case for example '"CreatedOnDateGMT"'
3. have a Hash Diff column where is_hashdiff: true
4. When the model builds the source_data and derived_columns CTEs are using the correct casing. The CONCAT_WS for the Hash is using the correct Casing. Only the column names being selected in the hashed_columns and columns_to_select are incorrect.

Expected behavior The column names should not be changed

Screenshots