message: Split out sccache environment as not all workflows use it.
  This fixes the audit workflow, which is incorrectly trying to use sccache currently.
diff: @@ -14,6 +14,11 @@ commands:
  echo 'export TAG=0.1.${CIRCLE_BUILD_NUM}' >> $BASH_ENV
  echo 'export IMAGE_NAME=myapp' >> $BASH_ENV
  echo 'export CARGO_INCREMENTAL=0' >> $BASH_ENV
  + sccache_setup:
  + steps:
  + - run:
  + name: Set Up sccache Environment
  + command: |
  echo 'export SCCACHE_CACHE_SIZE=2G' >> $BASH_ENV
  echo 'export RUSTC_WRAPPER=sccache' >> $BASH_ENV
  echo 'export CC="sccache cc"' >> $BASH_ENV
  @@ -44,6 +49,7 @@ jobs:
  resource_class: 2xlarge
  steps:
  - env_setup
  + - sccache_setup
  - restore_sccache_cache
  - run:
  name: Git Hooks and Checks
  