adding probably erroneously removed return value from execut_shell, giving 'None' in return always otherise - not ideal (#3212)

Co-authored-by: James Collins <collijk@uw.edu>

autogpt/commands/execute_code.py

@@ -133,6 +133,7 @@ def execute_shell(command_line: str) -> str:
     # Change back to whatever the prior working dir was
 
     os.chdir(current_dir)
+    return output
 
 
 @command(