message: Get UE for macOS from AWS S3 instead of Google GCS.
  macOS builds don't run on Google Cloud like Windows and Linux builds do,
  so downloading it from GCS isn't free. And GCS costs more than S3, so
  let's use S3.
diff: @@ -8,7 +8,7 @@ then
  rm Launcher.zip
  elif [[ $TRAVIS_OS_NAME == "osx" ]]
  then
  - AWS_ACCESS_KEY_ID=${GOOGLE_ACCESS_KEY_ID} AWS_SECRET_ACCESS_KEY=${GOOGLE_SECRET_ACCESS_KEY} aws s3 --endpoint-url https://storage.googleapis.com cp s3://cesium-unreal-engine/macos-2021-04-13/UE_4.26.tar.gz .
  + aws s3 cp s3://cesium-unreal-engine/macos-2021-04-13/UE_4.26.tar.gz .
  mkdir $HOME/UE_4.26
  tar xfz UE_4.26.tar.gz -C $HOME/UE_4.26
  rm UE_4.26.tar.gz
  