Feature/add inventory quantity

[fivetran-catfritz]

PR Overview

This PR will address the following Issue/Feature:

• Internal ticekt

This PR will result in the following new package version:

• 0.17.0 schema change

Please provide the finalized CHANGELOG entry which details the relevant changes included in this PR:

PR Checklist

Basic Validation

Please acknowledge that you have successfully performed the following commands locally:

• dbt run –full-refresh && dbt test
• dbt run (if incremental models are present) && dbt test

Before marking this PR as "ready for review" the following have been applied:

• The appropriate issue has been linked, tagged, and properly assigned
• All necessary documentation and version upgrades have been applied
• docs were regenerated (unless this PR does not include any code or yml updates)
• BuildKite integration tests are passing
• Detailed validation steps have been provided below

Detailed Validation

Please share any and all of your validation steps:

• Integrity tests pass, consistency fails as expected due to schema change
  

• Columns are populated when using test data
  

[fivetran-joemarkiewicz]

LGTM with a few minor suggestions!

[fivetran-reneeli]

Had just 1 suggestion!