TUN-3375: Upgrade coredns and prometheus dependencies

vendor/gopkg.in/yaml.v2/yamlh.go

@@ -579,6 +579,7 @@ type yaml_parser_t struct {
 
 	simple_key_allowed bool                // May a simple key occur at the current position?
 	simple_keys        []yaml_simple_key_t // The stack of simple keys.
+	simple_keys_by_tok map[int]int         // possible simple_key indexes indexed by token_number
 
 	// Parser stuff