add vendor data

vendor/github.com/dunglas/httpsfv/member.go

@@ -0,0 +1,9 @@
+package httpsfv
+
+// Member is a marker interface for members of dictionaries and lists.
+//
+// See https://httpwg.org/specs/rfc9651.html#list.
+type Member interface {
+	member()
+	marshaler
+}