fix: fix single quote unescape when the string is only quotes

[edenstrom]

This fixes #4349, where a column in the database has an empty value as the default.

Tested on MySQL

Not sure what tests to add for this though.

Table:

CREATE TABLE `countries` (
  `id` int NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL DEFAULT '',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=68 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

Result before:

name: varchar({ length: 255 }).default(').notNull(),

Result after:

name: varchar({ length: 255 }).default('').notNull(),

[monster-anshu]

Thanks much needed