chore: add PEP 249 reference link in databricks.sql package docstring

No functional change — adds a one-line comment linking to the PEP 249
spec next to the `apilevel`/`threadsafety`/`paramstyle` globals.

Opened to smoke-test the integration-tests workflow; will be closed
once CI completes.

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

Author: vikrantpuppala

src/databricks/sql/__init__.py

@@ -3,6 +3,7 @@
 from databricks.sql.exc import *
 
 # PEP 249 module globals
+# (see https://peps.python.org/pep-0249/#globals)
 apilevel = "2.0"
 threadsafety = 1  # Threads may share the module, but not connections.