Update dev-requirements.txt to use the dbt-adapters monorepo (#991)

* Update dev-requirements.txt for to resolve #990

* Update dev-requirements.txt to reflect `dbt-adapters` monorepo

Author: dbeatty10

dev-requirements.txt

@@ -2,9 +2,9 @@ pytest
 pytest-dotenv
 dbt-core@git+https://github.com/dbt-labs/dbt-core.git#subdirectory=core
 dbt-tests-adapter@git+https://github.com/dbt-labs/dbt-adapters.git#subdirectory=dbt-tests-adapter
-dbt-postgres@git+https://github.com/dbt-labs/dbt-postgres.git
-dbt-redshift@git+https://github.com/dbt-labs/dbt-redshift.git
-dbt-snowflake@git+https://github.com/dbt-labs/dbt-snowflake.git
-dbt-bigquery@git+https://github.com/dbt-labs/dbt-bigquery.git
+dbt-postgres@git+https://github.com/dbt-labs/dbt-adapters.git#subdirectory=dbt-postgres
+dbt-redshift@git+https://github.com/dbt-labs/dbt-adapters.git#subdirectory=dbt-redshift
+dbt-snowflake@git+https://github.com/dbt-labs/dbt-adapters.git#subdirectory=dbt-snowflake
+dbt-bigquery@git+https://github.com/dbt-labs/dbt-adapters.git#subdirectory=dbt-bigquery
 pytest-xdist
 tox>=3.13