add type boolean

[jpmmcneill]

resolves #315

required for dbt-labs/dbt-core#5739

Description

dbt-bigquery patch as required for dbt-labs/dbt-core#5739 via dbt-labs/dbt-core#5875.

Checklist

• I have read the contributing guide and understand what's expected of me
• I have signed the CLA
• 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 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

[dbeatty10]

This is looking awesome @jpmmcneill !

Here's the next steps for this PR:

1. Run changie new per these instructions and commit and push the resulting file.
2. Commit and push a change to dev-requirements.txt for the purposes of CI via GitHub Actions (see "Updating dev-requirements.txt" below for more details)
   • Since we'll want your adapter branch to be using your dbt-core PR branch rather than the main branch of dbt-core
3. Once all the PRs are passing CI and get approved, we'll merge the dbt-core PR first.
4. Then you'll undo your changes to dev-requirements.txt (and commit and push) and we'll re-run the CI tests in GitHub.
5. Once that is passing CI and gets approved, then it can be merged.

It will be the same process as above for dbt-redshift, dbt-snowflake, and dbt-spark. (Unfortunately, new tests aren't inherited and executed automatically -- they need to be added explicitly).

Updating dev-requirements.txt (temporarily)

Change these lines:

dbt-bigquery/dev-requirements.txt

Lines 3 to 4 in 61ed3b0

	git+https://github.com/dbt-labs/dbt-core.git#egg=dbt-core&subdirectory=core
	git+https://github.com/dbt-labs/dbt-core.git#egg=dbt-tests-adapter&subdirectory=tests/adapter

To this:

git+https://github.com/jpmmcneill/dbt-core.git@jpmmcneill/type-boolean#egg=dbt-core&subdirectory=core
git+https://github.com/jpmmcneill/dbt-core.git@jpmmcneill/type-boolean#egg=dbt-tests-adapter&subdirectory=tests/adapter

Then commit and push. CI in GitHub Actions should kick off here automatically.

[jpmmcneill]

@dbeatty10 thanks for the guides! This should be ready for a proper review now :)

[dbeatty10]

@jpmmcneill Now that dbt-labs/dbt-core#5875 has been merged, just two things and then this should be ready!

1. Click the "update branch" button (or merge the latest changes from main some other way)
2. Restore the original version of dbt-requirements.txt

If all looks good after CI runs, then we'll merge.