Node.js: fixed ES modules format in loader.mjs.

Before Node.js v16.14.0 the "format" value in defaultResolve
was ignored so error was hidden.  For more information see:
https://github.com/nodejs/node/pull/40980

docs/changes.xml

@@ -100,6 +100,12 @@ object, notably with Falcon.
 </para>
 </change>
 
+<change type="bugfix">
+<para>
+ECMAScript modules did not work with the recent Node.js versions.
+</para>
+</change>
+
 </changes>