feat: impl MCDatabase for mariadb

db/db-sqlx-maria/migrations/20210310122902_mcaptcha_levels.sql

@@ -0,0 +1,12 @@
+CREATE TABLE IF NOT EXISTS mcaptcha_levels (
+	config_id INTEGER NOT NULL,
+	difficulty_factor INTEGER NOT NULL,
+	visitor_threshold INTEGER NOT NULL,
+	level_id INT auto_increment,
+	PRIMARY KEY(level_id),
+	CONSTRAINT `fk_mcaptcha_config_id`
+		FOREIGN KEY (config_id)
+		REFERENCES mcaptcha_config (config_id)
+		ON DELETE CASCADE
+		ON UPDATE CASCADE
+);