After the latest update: v5.7.6.1918, the file size of mobilertc.aar has increased from 89MB to 126MB. As GitHub prevents file upload for files larger than 100MB, it is causing difficulties to maintain the project between different SDK versions. Not to mention the significant increase in app size.
One common approach to this sort of issue with GitHub is to use Git LFS. Additionally, if you are running into issues with the size of your final APK, here is a support article that may be useful.