scummvm: rename if there's version in file name

[Birdie0]

In new ScummVM release executable doesn't include version like that was it previous release, i.e. scummvm.exe instead of scummvm-2.9.0.exe. Because of this renaming added in #1124 results in error during installation (it still ends up successful). I think it's probably better to wrap rename command with condition in case user wants to install older version.

Here's installation log without change:

Updating one outdated app:
Updating 'scummvm' (2.8.1 -> 2.9.0)
Downloading new version
Starting download with aria2 ...
Download: Download Results:
Download: gid   |stat|avg speed  |path/URI
Download: ======+====+===========+=======================================================
Download: ff6093|OK  |   5.5MiB/s|C:/Users/User/scoop/cache/scummvm#2.9.0#83bb47a.zip
Download: Status Legend:
Download: (OK):download completed.
Checking hash of scummvm-2.9.0-win32-x86_64.zip ... ok.
Uninstalling 'scummvm' (2.8.1)
Unlinking ~\scoop\apps\scummvm\current
Installing 'scummvm' (2.9.0) [64bit] from 'games' bucket
Loading scummvm-2.9.0-win32-x86_64.zip from cache.
Extracting scummvm-2.9.0-win32-x86_64.zip ... done.
Running pre_install script...Rename-Item: Cannot find path 'C:\Users\User\scoop\apps\scummvm\2.9.0\scummvm-2.9.0.exe' because it does not exist.
done.
Linking ~\scoop\apps\scummvm\current => ~\scoop\apps\scummvm\2.9.0
Creating shortcut for ScummVM (scummvm.exe)
Persisting scummvm.ini
Persisting saves
Persisting themes
Persisting extras
'scummvm' (2.9.0) was installed successfully!

• I have read the Contributing Guide.

[github-actions]

All changes look good.

Wait for review from human collaborators.

scummvm

• Description
• License
• Hashes
• Checkver
• Autoupdate
• Autoupdate Hash Extraction

[Calinou]

Thanks!