Pre-release with GraphQL as the default

[fivetran-jamie]

PR Overview

Package version introduced in this PR:

• v0.20.0-a1
• v0.20.1-a1

A case could be made for this to be v0.19.1-a1 but it is in actuality rather breaking

This PR addresses the following Issue/Feature(s):

• Closes out GA-1000203

Summary of changes:

• Changes the default value of shopify_api to graphql so that Quickstart folks can try this out

Submission Checklist

• [ ] Alignment meeting with the reviewer (if needed)
  • [ ] Timeline and validation requirements discussed
• [ ] Provide validation details:
  • [ ] Validation Steps: Check for unintentional effects (e.g., add/run consistency & integrity tests)
  • [ ] Testing Instructions: Confirm the change addresses the issue(s)

Confirmed that dbt run without setting the shopify_api var runs the graphql models

• [ ] Focus Areas: Complex logic or queries that need extra attention
• [ ] Merge any relevant open PRs into this PR

Changelog

• [ ] Draft changelog for PR
• [ ] Final changelog for release review