Rudy Giuliani may be the mayor of Gotham, but Candice Bergen is getting ready to take over the gig for the big-screen, in Touchstone’s romantic comedy “Sweet Home Alabama.”Pic, directed by Andy Tennant (“Ever After”), stars Reese Witherspoon, Josh Lucas, Patrick Dempsey and Ethan Embry. Lensing begins Sunday in Gotham. Pic concerns a woman who leaves her husband in Alabama and opts for the New York lifestyle. Neal Moritz is producing; Jon Jashni and Wink Mordaunt are exec producers. Bergen, who hosts the Oxygen Network yakker “Exhale With Candice Bergen,” will next be seen in Miramax’s “A View From the Top.” She is repped by the William Morris Agency.