GOOS=linux when packaging

Signed-off-by: Sam Coward <scoward@pivotal.io>

Author: Tyler Phelan

scripts/build.sh

@@ -4,5 +4,5 @@ set -exuo pipefail
 cd "$( dirname "${BASH_SOURCE[0]}" )/.."
 source .envrc
 
-go build -ldflags="-s -w" -o bin/supply python/supply/cli
-go build -ldflags="-s -w" -o bin/finalize python/finalize/cli
+GOOS=linux go build -ldflags="-s -w" -o bin/supply python/supply/cli
+GOOS=linux go build -ldflags="-s -w" -o bin/finalize python/finalize/cli