Fix filter modifier form submission bug with 'action' field collision

Forms with a field named "action" (e.g., ObjectChangeFilterForm) were causing
the form.action property to be shadowed by the field element, resulting in
[object HTMLSelectElement] appearing in the URL path.

Use form.getAttribute('action') instead of form.action to reliably retrieve
the form's action URL without collision from form fields.

Fixes form submission on /core/changelog/ and any other forms with an 'action'
field using filter modifiers.

netbox/project-static/src/forms/filterModifiers.ts

@@ -37,7 +37,9 @@ export function initFilterModifiers(): void {
         }
       }
 
-      window.location.href = `${form.action}?${params.toString()}`;
+      // Use getAttribute to avoid collision with form fields named 'action'
+      const actionUrl = form.getAttribute('action') || form.action;
+      window.location.href = `${actionUrl}?${params.toString()}`;
     });
   }
 }