[feature] Add version number

**Suggestion:**
Show the version number in the title bar (the title bar seems like the best option, but somewhere else could also work).

**Why?**
Currently there is no (easy) way to see the version number using the GUI only. Adding it in the title bar would be could be very handy to check if you're on the latest version.

Start by locating the GUI window-title setup and the existing version definition in the scrcpy source. Check how the title is built and verify the result by launching the GUI and confirming that the version number is visible in the title bar.

Written by the indexing model from the issue text.