Volume expansivity of water is 2.1e-4/K, that of alcohol about 1e-3/K. So assume that beer is a little above water- say 2.5e-4/k. "Cold" beer won't be freezing, say it's 5C, and British "warm" beer is served a little below room temperature- say 15C. To the temperature difference is about 10 degrees. The volume expansion will be 2.5e-3 or a quarter of 1%, about 1.5ml in a (UK) pint glass. Just enough to drown a mosquito.