test(e2e): add databricks-sdk dev dependency for OAuth M2M auth

The e2e M2M auth (conftest.auth_connect_kwargs) imports
databricks.sdk.core.oauth_service_principal, but databricks-sdk was not a
project dependency, so `poetry install` in code-coverage.yml didn't provide
it -- every e2e connection failed with `ModuleNotFoundError: No module named
'databricks.sdk'`. Add it to the dev group (test-only; not a runtime dep of
the connector). CI's setup-poetry runs `poetry lock` before install, so the
lockfile is regenerated on the runner.

Co-authored-by: Isaac
Signed-off-by: Vikrant Puppala <vikrant.puppala@databricks.com>

Author: vikrantpuppala

pyproject.toml

@@ -93,6 +93,13 @@ black = "^22.3.0"
 pytest-dotenv = "^0.5.2"
 pytest-cov = "^4.0.0"
 pytest-xdist = "^3.0.0"
+# Test-only: the e2e suite authenticates to the warehouse via OAuth M2M
+# (service principal) using databricks.sdk's oauth_service_principal — see
+# conftest.auth_connect_kwargs. The connector itself has no native
+# Databricks-OAuth M2M path (its azure-sp-m2m targets Azure AD; its
+# databricks-oauth path is interactive U2M), so the SDK provides the
+# client-credentials flow against /oidc/v1/token. Not a runtime dependency.
+databricks-sdk = ">=0.20"
 numpy = [
     { version = ">=1.16.6", python = ">=3.8,<3.11" },
     { version = ">=1.23.4", python = ">=3.11" },