Add constraint name to migration script

fractal_server/migrations/versions/dfbe4f3a7bc4_init_user_settings.py

@@ -17,6 +17,9 @@
 depends_on = None
 
 
+CONSTRAINT_NAME = "fk_user_oauth_user_settings_id_user_settings"
+
+
 def upgrade() -> None:
     # ### commands auto generated by Alembic - please adjust! ###
     op.create_table(
@@ -46,7 +49,7 @@ def upgrade() -> None:
             sa.Column("user_settings_id", sa.Integer(), nullable=True)
         )
         batch_op.create_foreign_key(
-            None, "user_settings", ["user_settings_id"], ["id"]
+            CONSTRAINT_NAME, "user_settings", ["user_settings_id"], ["id"]
         )
 
     # ### end Alembic commands ###
@@ -55,7 +58,7 @@ def upgrade() -> None:
 def downgrade() -> None:
     # ### commands auto generated by Alembic - please adjust! ###
     with op.batch_alter_table("user_oauth", schema=None) as batch_op:
-        batch_op.drop_constraint(None, type_="foreignkey")
+        batch_op.drop_constraint(CONSTRAINT_NAME, type_="foreignkey")
         batch_op.drop_column("user_settings_id")
 
     op.drop_table("user_settings")