Include 429, standard.

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    ghx (0.2.1)
+    ghx (0.3.0)
       faraday (~> 2.9.0)
       faraday-retry (~> 2.2.1)
       octokit

lib/ghx/errors.rb

@@ -1,5 +1,7 @@
 module GHX
   class GHXError < StandardError; end
+
   class RateLimitExceededError < GHXError; end
+
   class OtherApiError < GHXError; end
-end
+end

lib/ghx/rest_client.rb

@@ -71,7 +71,7 @@ def _http_request(uri:, request:)
 
       if response.code.to_i < 400
         response
-      elsif response.code.to_i == 403
+      elsif [403, 429].include?(response.code.to_i)
         if response["X-RateLimit-Remaining"].to_i == 0
           reset_time = Time.at(response["X-RateLimit-Reset"].to_i)
           raise GHX::RateLimitExceededError, "GitHub API rate limit exceeded. Try again after #{reset_time}"
@@ -82,6 +82,5 @@ def _http_request(uri:, request:)
         raise GHX::OtherApiError, "GitHub API returned an error: #{response.code} #{response.body}"
       end
     end
-
   end
 end