Convert mix of JSON.parse and JSON.load_file (#38242)

lib/vite_ruby/sri_extensions.rb

@@ -15,7 +15,7 @@ module ViteRuby::ManifestIntegrityExtension
   end
 
   def load_name_lookup_cache
-    Oj.load(config.build_output_dir.join('.vite/manifest-lookup.json').read)
+    JSON.load_file(config.build_output_dir.join('.vite/manifest-lookup.json'))
   end
 
   # Upstream's `virtual` type is a hack, re-implement it with efficient exact name lookup