Fix app build issue - Chicago Commutes

Trying to fix the build issue regarding https://f-droid.org/wiki/page/fr.cph.chicago.foss/lastbuild_161

I'm not 100% sure this will fix it because I do not obtain the exact same error in local, but:

• I added a buildSrc folder into my app and that thread: https://forum.f-droid.org/t/found-java-compiled-class-at-buildsrc/4179 seems to point to something that needs to be addressed anyway.
• The app build correctly with that fix in local.

If you think the approach is wrong, or if you think this is something else, please let me know.