Fix syntax error in f-string in silicon.py

Fixed a syntax error in the f-string on line 189 where double quotes
were used inside double quotes, which was causing coverage.py to be
unable to parse the file.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: robtaylor

chipflow_lib/steps/silicon.py

@@ -186,7 +186,7 @@ def submit(self, rtlil_path, *, dry_run=False):
         # Handle response based on status code
         if resp.status_code == 200:
             logger.info(f"Submitted design: {resp_data}")
-            print(f"https://{host}/build/{resp_data["build_id"]}")
+            print(f"https://{host}/build/{resp_data['build_id']}")
 
         else:
             # Log detailed information about the failed request