CAMBRIDGE - Gavin Peters came home last week to find a note on his door. It was from a Cambridge city inspector, and it asked Peters to call him “regarding your pool.’’ On Friday, his “children’s wading pool,’’ as the inspector referred to it, received six citations for violating the city’s building, zoning and sanitary codes, and he was given seven days to remove it. The problem, according to Peters, is that he doesn’t have a pool in his yard. He has an ice rink. Or at least he was supposed to. In this weirdest of winters, the Peters citation is just the latest sign of a season that wasn’t.