fix: associate challenges with usernames

db/db-sqlx-postgres/migrations/20230610105810_mcaptcha_challenge.sql

@@ -6,6 +6,7 @@ CREATE TABLE IF NOT EXISTS mcaptcha_challenge_reason (
 CREATE TABLE IF NOT EXISTS mcaptcha_challenge (
 	id SERIAL PRIMARY KEY NOT NULL,
 	reason INTEGER NOT NULL references mcaptcha_challenge_reason(ID) ON DELETE CASCADE,
+	user_id INTEGER NOT NULL references mcaptcha_users(ID) ON DELETE CASCADE,
 	challenge_id varchar(40) NOT NULL UNIQUE,
 	received timestamptz NOT NULL DEFAULT now()
 );