Fix mistake in database v4. Fixes #10

database/upgrades/00-latest-revision.sql

@@ -1,4 +1,4 @@
--- v0 -> v4: Latest revision
+-- v0 -> v5: Latest revision
 
 CREATE TABLE guild (
     dcid       TEXT PRIMARY KEY,

database/upgrades/05-reaction-fkey-fix.sql

@@ -0,0 +1,8 @@
+-- v5: Fix foreign key broken in v4
+-- only: postgres
+
+ALTER TABLE reaction DROP CONSTRAINT reaction_message_fkey;
+ALTER TABLE reaction ADD CONSTRAINT reaction_message_fkey
+    FOREIGN KEY (dc_msg_id, dc_first_attachment_id, _dc_first_edit_index, dc_chan_id, dc_chan_receiver)
+        REFERENCES message(dcid, dc_attachment_id, dc_edit_index, dc_chan_id, dc_chan_receiver)
+        ON DELETE CASCADE;