Use utf8mb4 collation and charset

convert.py

@@ -86,10 +86,10 @@ def write_header(file):
     file.write("DROP TABLE IF EXISTS `store`;\n")
     file.write(
 """CREATE TABLE `store` (
-    `key` varchar(100) COLLATE utf8_bin NOT NULL DEFAULT '',
-    `value` longtext COLLATE utf8_bin NOT NULL,
+    `key` varchar(100) COLLATE utf8mb4_bin NOT NULL DEFAULT '',
+    `value` longtext COLLATE utf8mb4_bin NOT NULL,
     PRIMARY KEY (`key`)
-) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;
 """)
     file.write("LOCK TABLES `store` WRITE;\n")