Remove heroku bin/pre_compile file (#4900)

bin/pre_compile

@@ -1,18 +0,0 @@
-#!/usr/bin/env bash
-# Heroku pre_compile script
-
-DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
-pushd $DIR/..
-
-# heroku requires cffi to be in requirements.txt in order for libffi to be installed.
-# https://github.com/heroku/heroku-buildpack-python/blob/master/bin/steps/cryptography
-# to avoid making it a requirement for other build systems, we'll inject it now
-# into the requirements.txt file
-
-# Remove Heroku unsupported Python packages:
-grep -v -E "^(pymssql|thrift|sasl|pyhive)" requirements_all_ds.txt >> requirements.txt
-
-# make the heroku Procfile the active one
-cp Procfile.heroku Procfile
-
-popd