chore(buildpacks): update heroku-buildpack-scala to v75

See heroku/heroku-buildpack-scala@v72...v75

Author: mboersma

rootfs/builder/install-buildpacks

@@ -39,4 +39,4 @@ download_buildpack https://github.com/heroku/heroku-buildpack-php.git
 download_buildpack https://github.com/heroku/heroku-buildpack-play.git           v26      09-play
 download_buildpack https://github.com/heroku/heroku-buildpack-python.git         v97      10-python
 download_buildpack https://github.com/heroku/heroku-buildpack-ruby.git           v153     11-ruby
-download_buildpack https://github.com/heroku/heroku-buildpack-scala.git          v72      12-scala
+download_buildpack https://github.com/heroku/heroku-buildpack-scala.git          v75      12-scala