The short answer is yes, but the way to do it might involve utilizing one of GarageBand's more advanced features, Flex Time.. If you're using ONLY Software Instruments then it's easy enough—you'd just change the global Tempo [speed it up slightly] until the song fits within the desired time frame. If you're using Audio tracks, or both Software Instrument tracks and Audio tracks, then you might have to take an extra step—you'd also have to make sure that Flex Time is enabled for all Audio tracks and the option 'Follow Tempo & Pitch' is enabled on all the Audio Regions on all the Audio tracks, so they'll also follow any global Tempo change [otherwise they'd get out of sync with Software Instrument tracks when the Tempo is adjusted]. GarageBand might enable those settings automatically if you start adjusting the Tempo, but if it doesn't sometimes you'd have to set them manually. Those settings are found in the Editor pane at the bottom, opened via the 'E' key. The 'Enable Flex' option is done for each [selected] track, and the 'Follow Tempo & Pitch' is done for each individual [selected] Region.