BREAKING CHANGE(core): switch to esm

ts/index.ts

@@ -1,15 +1,15 @@
-import * as plugins from './smartyaml.plugins';
+import * as plugins from './smartyaml.plugins.js';
 
 export let yamlStringToObject = async (
   yamlStringArg,
   optionsArg: plugins.jsYaml.LoadOptions = {}
 ): Promise<any> => {
-  return plugins.jsYaml.safeLoad(yamlStringArg);
+  return plugins.jsYaml.load(yamlStringArg);
 };
 
 export let objectToYamlString = async (
   objectArg,
   optionsArg: plugins.jsYaml.DumpOptions = {}
 ): Promise<string> => {
-  return plugins.jsYaml.safeDump(objectArg);
+  return plugins.jsYaml.dump(objectArg);
 };