Ignore disabled file input

Disabled file input form should be ignored,
however currently submitting a form with disabled file input
will cause issue on Rails' side.

src/rails.js

@@ -48,7 +48,7 @@
     requiredInputSelector: 'input[name][required]:not([disabled]),textarea[name][required]:not([disabled])',
 
     // Form file input elements
-    fileInputSelector: 'input[type=file]',
+    fileInputSelector: 'input[type=file]:not([disabled])',
 
     // Link onClick disable selector with possible reenable after remote submission
     linkDisableSelector: 'a[data-disable-with], a[data-disable]',