Remove es6 package.json because it's already the default

Author: shulhi

packages/@rescript/runtime/lib/es6/package.json

@@ -191,7 +191,6 @@
     "lib/es6/Stdlib_Uint8ClampedArray.js",
     "lib/es6/Stdlib_WeakMap.js",
     "lib/es6/Stdlib_WeakSet.js",
-    "lib/es6/package.json",
     "lib/js/Belt.js",
     "lib/js/Belt_Array.js",
     "lib/js/Belt_Float.js",
@@ -1241,4 +1240,4 @@
     "lib/ocaml/Stdlib_WeakSet.res",
     "package.json"
   ]
-}
+}