Wholesale prices, pushed upward by large increases for gasoline and home heating oil but restrained by a second straight month of stagnant food costs, rose a modest 0.3 percent in November, the government said Friday. The increase would amount to 3.3 percent if it persisted for 12 months. Prices had held flat in October. For the first 11 months of 1988, prices one step short of the retail level were up 3.8 percent, an indication that no significant surge in prices was just over the horizon. Prices had risen 2.2 percent for all of 1987.