Ant Anstead celebrated son Hudson’s 7th birthday with a rare look at the youngster spending time his girlfriend, Renée Zellweger. The former “Wheeler Dealers” co-host took to Instagram Sunday to share a montage of photos and videos of Hudson through the years, with Zellweger making a few appearances alongside the birthday boy. Among the collection was a selfie of Anstead, Zellweger and Hudson, with Anstead and Zellweger sporting leis around their necks. Zellweger, 57, wore oversized heart-shaped bejeweled glasses and a mini ringleader hat, while Hudson beamed in a handmade yellow rhinestone paper crown. In another clip, Zellweger and…