[core] Strip name of game installation folder

Thanks Kerbal Space Program for having an invalid
directory name as your set folder!

legendary/core.py

@@ -1383,7 +1383,7 @@ def prepare_download(self, game: Game, base_game: Game = None, base_path: str =
                 self.log.info(f'"{base_path}" does not exist, creating...')
                 os.makedirs(base_path)
 
-            install_path = os.path.normpath(os.path.join(base_path, game_folder))
+            install_path = os.path.normpath(os.path.join(base_path, game_folder.strip()))
 
         # check for write access on the install path or its parent directory if it doesn't exist yet
         base_path = os.path.dirname(install_path)