Fix incorrect module reference in migration docs

Fix incorrect module reference (`sa_exc` instead of `exc`) in migration docs.

Found in page: https://docs.sqlalchemy.org/en/14/changelog/migration_20.html

diff --git a/doc/build/changelog/migration_20.rst b/doc/build/changelog/migration_20.rst
index a59d5b677d662ec0a9d45d448700c9d30a3045fa..6e349c8e83399e13c953c5058ab9a5fa5f90825b 100644 (file)
--- a/doc/build/changelog/migration_20.rst
+++ b/doc/build/changelog/migration_20.rst
@@ -268,7 +268,7 @@ the SQLAlchemy project itself, the approach taken is as follows:
             r".*DefaultGenerator.execute\(\)",
         ]:
           warnings.filterwarnings(
-              "error", message=msg, category=sa_exc.RemovedIn20Warning,
+              "error", message=msg, category=exc.RemovedIn20Warning,
           )
 
         # for all other warnings, just log