Add size-only flag to aws s3 sync

This will avoid re-upload if the file size doesn't change. Currently the
check on mtime is not very useful, as the local time of last
modification never will match the upload mtime on S3.

A better/safer mechanism would be to hash the file content and store it
as e-tag. These tickets discuss such a feature, but it isn't implemented
yet:
- aws/aws-cli#599
- aws/aws-cli#575

Makefile

@@ -34,7 +34,7 @@ prod-frontend-release:
 	yarn shadow-cljs release frontend --config-merge '$(PROD_CONFIG)'
 
 prod-frontend-deploy: check-before-deploy-frontend prod-frontend-release
-	aws --profile heraldry-serverless s3 sync --acl public-read $(PROD_FRONTEND_RELEASE_DIR) s3://cdn.heraldry.digital
+	aws --profile heraldry-serverless s3 sync --size-only --acl public-read $(PROD_FRONTEND_RELEASE_DIR) s3://cdn.heraldry.digital
 	aws --profile heraldry-serverless s3 cp --acl public-read $(PROD_FRONTEND_RELEASE_DIR)/index.html s3://cdn.heraldry.digital/index.html --metadata-directive REPLACE --cache-control max-age=0,no-cache,no-store,must-revalidate --content-type text/html
 	git tag $(shell date +"deploy-frontend-%Y-%m-%d_%H-%M-%S")
 	./invalidate-distribution.sh cdn.heraldry.digital
@@ -63,7 +63,7 @@ staging-frontend-release:
 	yarn shadow-cljs release frontend --config-merge '$(STAGING_CONFIG)' --config-merge '{:output-dir "./build/staging/js/generated"}'
 
 staging-frontend-deploy: staging-frontend-release
-	aws --profile heraldry-serverless s3 sync --acl public-read $(STAGING_FRONTEND_RELEASE_DIR) s3://cdn.staging.heraldry.digital
+	aws --profile heraldry-serverless s3 sync --size-only --acl public-read $(STAGING_FRONTEND_RELEASE_DIR) s3://cdn.staging.heraldry.digital
 	aws --profile heraldry-serverless s3 cp --acl public-read $(STAGING_FRONTEND_RELEASE_DIR)/index.html s3://cdn.staging.heraldry.digital/index.html --metadata-directive REPLACE --cache-control max-age=0,no-cache,no-store,must-revalidate --content-type text/html
 	./invalidate-distribution.sh cdn.staging.heraldry.digital