chore(buildpacks): update heroku-buildpack-scala to v71

See heroku/heroku-buildpack-scala@v70...v71

Author: mboersma

rootfs/builder/install-buildpacks

@@ -38,5 +38,5 @@ download_buildpack https://github.com/heroku/heroku-buildpack-play.git
 download_buildpack https://github.com/heroku/heroku-buildpack-python.git         v81
 download_buildpack https://github.com/heroku/heroku-buildpack-php.git            v108
 download_buildpack https://github.com/heroku/heroku-buildpack-clojure.git        v75
-download_buildpack https://github.com/heroku/heroku-buildpack-scala.git          v70
+download_buildpack https://github.com/heroku/heroku-buildpack-scala.git          v71
 download_buildpack https://github.com/heroku/heroku-buildpack-go.git             v42