Standardize dev requirements

[mikealfare]

Description

Unpin dev requirements. These requirements are not part of the release and tend to cause version conflicts and several dependabot alerts. While pinning the production requirements makes sense, we should always be using the most current version of dev requirements by default.

Checklist

• [x] I have read the contributing guide and understand what's expected of me
• [x] I have signed the CLA
• [ ] I have run this code in development and it appears to resolve the stated issue
• [x] This PR includes tests, or tests are not required/relevant for this PR
• [x] I have opened an issue to add/update docs, or docs changes are not required/relevant for this PR
• [ ] I have run changie new to create a changelog entry

[github-actions[bot]]

Thank you for your pull request! We could not find a changelog entry for this change. For details on how to document a change, see the dbt-spark contributing guide.