[Fix] U3d::Utils: replace Ruby agent with another one to bypass 403 from Unity

Author: Paul Niezborala

lib/u3d/utils.rb

@@ -34,6 +34,9 @@ module Utils
     # Regex to capture each part of a version string (0.0.0x0)
     CSIDL_LOCAL_APPDATA = 0x001c
     UNITY_VERSION_REGEX = /(\d+)(?:\.(\d+)(?:\.(\d+))?)?(?:(\w)(?:(\d+))?)?/.freeze
+    MOZILLA_AGENT_HEADER = {
+      'User-Agent' => 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:106.0) Gecko/20100101 Firefox/106.0'
+    }.freeze
 
     class << self
       def final_url(url, redirect_limit: 10)
@@ -56,6 +59,9 @@ def page_content(url, redirect_limit: 10, request_headers: {})
       def follow_redirects(url, redirect_limit: 10, http_method: :get, request_headers: {}, &block)
         raise 'Too many redirections' if redirect_limit.zero?
 
+        # Unity blocks the default Ruby agent, use another one
+        request_headers = MOZILLA_AGENT_HEADER.merge(request_headers)
+
         response = nil
         request = nil
         uri = URI(url)