docs: update base version to 0.137.0

Author: Haleclipse

README.md

@@ -27,7 +27,7 @@ This fork includes the following enhancements over the upstream [openai/codex](h
 
 ## Upstream Sync
 
-This fork is regularly synced with the upstream OpenAI Codex repository. Current base: **0.136.0**.
+This fork is regularly synced with the upstream OpenAI Codex repository. Current base: **0.137.0**.
 
 ## Using Codex with your ChatGPT plan