app: added helm tgz handle

vendor/github.com/go-openapi/swag/string_bytes.go

@@ -0,0 +1,8 @@
+package swag
+
+import "unsafe"
+
+// hackStringBytes returns the (unsafe) underlying bytes slice of a string.
+func hackStringBytes(str string) []byte {
+	return unsafe.Slice(unsafe.StringData(str), len(str))
+}