update install_requires to allow for pre-release common/adapters (#727)

setup.py

@@ -48,8 +48,8 @@ def _plugin_version() -> str:
     packages=find_namespace_packages(include=["dbt", "dbt.*"]),
     include_package_data=True,
     install_requires=[
-        "dbt-common<2.0",
-        "dbt-adapters<2.0",
+        "dbt-common>=0.1.0a1,<2.0",
+        "dbt-adapters>=0.1.0a1,<2.0",
         f"dbt-postgres~={_plugin_version()}",
         # dbt-redshift depends deeply on this package. it does not follow SemVer, therefore there have been breaking changes in previous patch releases
         # Pin to the patch or minor version, and bump in each new minor version of dbt-redshift.