[Drizzle Kit][Pg]: Altering a UNIQUE constraint: generated SQL ignores the new changes

[CedricDsmet]

Fixes #5585

The cause of the bug seems to be at

drizzle-orm/drizzle-kit/src/dialects/postgres/convertor.ts

Line 701 in 1a01082

statements.push(addUniqueConvertor.convert({ unique: st.diff.$left }) as string);

const alterUniqueConvertor = convertor('alter_unique', (st) => {
	const statements: string[] = [];

	statements.push(dropUniqueConvertor.convert({ unique: st.diff.$left }) as string);
	statements.push(addUniqueConvertor.convert({ unique: st.diff.$left }) as string); // --> st.diff.$left should be change to st.diff.$right

	return statements;
});