fix: benchmark_migration.py needs to close sssion (#15822)

diff --git a/scripts/benchmark_migration.py b/scripts/benchmark_migration.py
index 163fc29..d721ba5 100644
--- a/scripts/benchmark_migration.py
+++ b/scripts/benchmark_migration.py
@@ -172,6 +172,7 @@
         rows = session.query(model).count()
         print(f"- {model.__name__} ({rows} rows in table {model.__tablename__})")
         model_rows[model] = rows
+    session.close()
 
     print("Benchmarking migration")
     results: Dict[str, float] = {}
diff --git a/superset/migrations/versions/301362411006_add_execution_id_to_report_execution_.py b/superset/migrations/versions/301362411006_add_execution_id_to_report_execution_.py
index eff2ff0..3edc52f 100644
--- a/superset/migrations/versions/301362411006_add_execution_id_to_report_execution_.py
+++ b/superset/migrations/versions/301362411006_add_execution_id_to_report_execution_.py
@@ -32,8 +32,10 @@
 
 
 def upgrade():
-    op.add_column("report_execution_log", sa.Column("uuid", UUIDType(binary=True)))
+    with op.batch_alter_table("report_execution_log") as batch_op:
+        batch_op.add_column(sa.Column("uuid", UUIDType(binary=True)))
 
 
 def downgrade():
-    op.drop_column("report_execution_log", "uuid")
+    with op.batch_alter_table("report_execution_log") as batch_op:
+        batch_op.drop_column("uuid")