Explicitely convert icon Path to string

Author: ReijerBoodt

src/wagtail_heroicons/wagtail_hooks.py

@@ -11,5 +11,5 @@
 @hooks.register("register_icons")
 def register_icons(icons):
     for icon in Heroicon.get_icons():
-        icons.append(icon.path)
+        icons.append(str(icon.path))
     return icons