[`rTexPacker`] Can't export to binary from command-line

[Shaka-Rule]

When running the following command:
rtexpacker -i Sprites -o Atlas.rtpb

It gives me this warning and outputs as the default rtpa format:
WARNING: Output file format not valid, must be .rtpa/.xml/.json file

[raysan5]

@Shaka-Rule Reviewed this issue, in my code is fixed, no idea when I fixed it... It should work on next release.