Fix %cs showing instead of commit date on Windows (or older git?)

Whenever I'd compile on Windows, I'd see the literal text "%cs" in the
main menu instead of the commit date. I never thought much of it (at
least it runs, and the date only shows up in development builds). Now
that I've also seen a screenshot from Terry with it, I decided to look
into it further. Looks like it's a format string that our gits on
Windows aren't recognizing for whatever reason - probably because
they're too old. I have git version 2.23.0.windows.1, and checking its
help page for `git log`, under PRETTY FORMATS, %cs is missing as an
option, while some other options are still there. So the option was
probably added sometime between that version and 2.34.1, which is the
one I have on Linux, where %cs does work.

Luckily, %cd with --date=short seems equivalent, and better supported,
so we can just use that instead.

desktop_version/version.cmake

@@ -8,7 +8,7 @@ EXECUTE_PROCESS(
 )
 
 EXECUTE_PROCESS(
-    COMMAND "${GIT_EXECUTABLE}" log -1 --format=%cs
+    COMMAND "${GIT_EXECUTABLE}" log -1 --format=%cd --date=short
     OUTPUT_VARIABLE COMMIT_DATE
     OUTPUT_STRIP_TRAILING_WHITESPACE
 )