actions: labeler: Add new "GitHub" label for auto-labeling · armbian/build@6371e92

Cannot update "Needs Documentation" label: Validation Failed: {"resource":"Label","code":"invalid","field":"color"}

Cannot update "Documentation finished" label: Validation Failed: {"resource":"Label","code":"invalid","field":"color"}

Cannot update "Improper usage" label: Validation Failed: {"resource":"Label","code":"invalid","field":"color"}