Remove GOPROXY from release branch workflow (#1024)

Author: dhurley

.github/workflows/release-branch.yml

@@ -71,7 +71,6 @@ on:
 
 env:
   NFPM_VERSION: 'v2.35.3'
-  GOPROXY: "https://${{ secrets.ARTIFACTORY_USER }}:${{ secrets.ARTIFACTORY_TOKEN }}@azr.artifactory.f5net.com/artifactory/api/go/f5-nginx-go-dev"
 
 defaults:
   run: