try fix again again again again again.

database/postgres/migrations/20210726221410_make_post_position_index_deferrable.sql

@@ -0,0 +1,13 @@
+-- +goose Up
+-- +goose StatementBegin
+ALTER TABLE log_post
+    DROP CONSTRAINT log_post_log_short_id_position_key,
+    ADD  CONSTRAINT log_post_log_short_id_position_key UNIQUE(log_short_id, position) DEFERRABLE;
+-- +goose StatementEnd
+
+-- +goose Down
+-- +goose StatementBegin
+ALTER TABLE log_post
+    DROP CONSTRAINT log_post_log_short_id_position_key,
+    ADD  CONSTRAINT log_post_log_short_id_position_key UNIQUE(log_short_id, position);
+-- +goose StatementEnd