chore(buildpacks): update heroku-buildpack-java to v48

See heroku/heroku-buildpack-java@v46...v48

Author: mboersma

rootfs/builder/install-buildpacks

@@ -31,7 +31,7 @@ mkdir -p $BUILDPACK_INSTALL_PATH
 download_buildpack https://github.com/heroku/heroku-buildpack-multi.git          v1.0.0
 download_buildpack https://github.com/heroku/heroku-buildpack-ruby.git           v148
 download_buildpack https://github.com/heroku/heroku-buildpack-nodejs.git         v91
-download_buildpack https://github.com/heroku/heroku-buildpack-java.git           v46
+download_buildpack https://github.com/heroku/heroku-buildpack-java.git           v48
 download_buildpack https://github.com/heroku/heroku-buildpack-gradle.git         v18
 download_buildpack https://github.com/heroku/heroku-buildpack-grails.git         v20
 download_buildpack https://github.com/heroku/heroku-buildpack-play.git           v26