Any software which will re-mux video (copying the video stream rather than re-encoding) should be able to change the frame rate in the process.Yamb
MKVMergeGUI for MKVs. It's part of MKVToolNix
(MKVMergeGUI will also open other file types such as MP4 and AVI and re-mux them as MKVs)Virtualdub
for AVIs (you need to select "direct stream copy" from the video menu after changing the frame rate).
If it doesn't matter if the re-muxed video is an MKV rather than an MP4, MKVMergeGUI is easier to use and faster than YAMB.
Of course the above will only change the frame rate of the video. If there's an audio stream which you need to keep in sync with the video then you'd probably need to re-encode it while changing it's speed to match. Getting that right can be a bit of a process. MKVMergeGUI does have a function for time stretching the audio stream, but how successfully it works depends on the type of audio.