feat: constraints support and new tests

[ptiurin]

Resolves #103

Description

Adding new tests and constraints support to be compatible with dbt 1.5

Setting threads to 1 in order to avoid race conditions when multiple tests use the same table name. Once we have user schema support we can re enable it in order to speed up the testing.

Bumping Python version from 3.7 to 3.9, since there are some issues with inheritance resolution in pytest - overrides are not taken into account and base class fixtures and tests are run therefore failing the whole test suite.

Checklist

• 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.
• I have run changie new and committed everything in .changes folder
• I have removed any print or log calls that were added for debugging.
• I have verified that this PR contains only code changes relevant to this PR.
• If further integration tests are now passing I've edited tests/functional/adapter/* to account for this.
• I have pulled/merged from the main branch if there are merge conflicts.
• After pulling/merging main I have run pytest on the included or updated tests/functional/adapter/.

[sonarcloud]

Quality Gate passed

The SonarCloud Quality Gate passed, but some issues were introduced.

3 New issues
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud