add default AWS region for SCCACHE

Author: wdvr

.github/workflows/docker-builds.yml

@@ -26,6 +26,9 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.sha }}-${{ github.event_name == 'workflow_dispatch' }}
   cancel-in-progress: true
 
+env:
+  AWS_DEFAULT_REGION: us-east-1
+
 jobs:
   docker-build:
     runs-on: [self-hosted, linux.2xlarge]