OBS Studio's current version is show as 31.0.2. That's correct. It says that 31.0.3 is available. There is no such version.
OBS Studio Version 31.0.3 was released on GitHub four days ago.
https://github.com/obsproject/obs-studio/releases/tag/31.0.3 (https://github.com/obsproject/obs-studio/releases/tag/31.0.3)