chore(builder): update heroku-buildpack-java to v38

Author: mboersma

builder/image/slugbuilder/builder/install-buildpacks

@@ -31,7 +31,7 @@ mkdir -p $BUILDPACK_INSTALL_PATH
 download_buildpack https://github.com/ddollar/heroku-buildpack-multi.git         6e79094
 download_buildpack https://github.com/heroku/heroku-buildpack-ruby.git           v137
 download_buildpack https://github.com/heroku/heroku-buildpack-nodejs.git         v75
-download_buildpack https://github.com/heroku/heroku-buildpack-java.git           v32
+download_buildpack https://github.com/heroku/heroku-buildpack-java.git           v38
 download_buildpack https://github.com/heroku/heroku-buildpack-gradle.git         v12
 download_buildpack https://github.com/heroku/heroku-buildpack-grails.git         1ef927d
 download_buildpack https://github.com/heroku/heroku-buildpack-play.git           v22