Mayor Zohran Mamdani is pleading with the City Council to sign off on a budget extension — as the freshman city leader scrambles to try to milk Albany for more money with his wish list of new taxes DOA, The Post has learned. Sources said Speaker Julie Menin — who has been a check on the mayor’s bloated budget spending — agreed to the request, with the caveat of the socialist mayor agreeing to find savings to fill the nearly $6 billion gap. Hizzoner requested the delay from the council with