how do i match tempo without pitch changing?

Some groove clips are configured as pitched, and the native pitch is part of the clip's groove configuration. Then they follow the current key signature of the project, or some interval you can modify for the clip. Other groove clips are configured as not pitched, so they don't get transposed. You can modify the pitch or remove the pitch by operating on the clip in the groove editing window, usually accessed by double-clicking the clip.
 
A slightly different approach would be to turn off grooving and use the stretch tool instead, which can change the clip length with no change in pitch.

Place the clip so it begins where you want it. Then place your cursor just before the end of the clip while holding ctrl + shift. When you see a funny looking cursor that looks like it should refer to clip stretching (!?) click and drag the end of the clip to stretch it or shrink it so it fits where you want it. It helps quite a bit if you start by setting the snap resolution to a unit that will help you land where you want it.