Skip inapplicable test that compares dbt-core's version to that of dbt-postgres

[mikealfare]

Problem

The test compares dbt-core's version to that of dbt-postgres. This is not always true though, as different versions could be published to PyPI at the same time.

Solution

• Manually inspect the test to ensure the actual expected version is there
• Skip the test
• Release
• Resolve the test in the future, or elect to remove it as these two packages are now decoupled

Checklist

• I have read the contributing guide and understand what's expected of me
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc) or this PR has already received feedback and approval from Product or DX