perform certain actions only on the upstream repo

Signed-off-by: Kenneth Bingham <kenneth.bingham@netfoundry.io>

magefile.go

@@ -140,7 +140,7 @@ func Release() error {
 	var args []string
 	args = append(args, "release", "--clean")
 
-	if os.Getenv("GITHUB_REPOSITORY_OWNER") != "helm" {
+	if os.Getenv("GITHUB_REPOSITORY") != "helm/chart-releaser" {
 		args = append(args, "--skip=docker,homebrew")
 	}