prometheus: add authorization section

nixos/modules/services/monitoring/prometheus/default.nix

@@ -251,6 +251,13 @@ let
 
   promTypes.scrape_config = types.submodule {
     options = {
+      authorization = mkOption {
+        type = types.attrs;
+        default = {};
+        description = ''
+          Sets the `Authorization` header on every scrape request with the configured credentials.
+        '';
+      };
       job_name = mkOption {
         type = types.str;
         description = ''