fix: fix migrator recognizing nextval('"table_column_seq"'::regclass)

[ifrvn]

• Do only one thing
• Non breaking API changes
• Tested

What did this pull request do?

Using SERIAL to create an auto-incrementing integer column will set the default value as nextval('"table_column_seq"'::regclass) which contains double quotes. Current codes only check cases without double quotes. This PR should fix the problem.

User Case Description

CREATE TABLE public."User" (
	id serial NOT NULL,
	CONSTRAINT user_pk PRIMARY KEY (id)
);

The default value of the id column would be nextval('"User_id_seq"'::regclass)

Related issue go-gorm/gen#1272