Update migration to ensure walker is refreshed after finder prefix was added. (#425)

* Update migration that looks for prefix with '.' as it matches the other prefixes in the file. Also mod walker prefix to use double quotes for consistency to match the others.

* Rename fixed migration to ensure it runs again for all users

config/walker/config.toml

@@ -213,7 +213,7 @@ concurrency = 8
 show_icon_when_single = true
 preview_images = true
 hidden = false
-prefix = '.'
+prefix = "."
 
 [builtins.runner]
 eager_loading = true