fix: Close f_open handle if background image found

radio/src/gui/colorlcd/theme_manager.cpp

@@ -305,6 +305,7 @@ void ThemeFile::applyBackground()
     FRESULT result = f_open(&file, rootDir.c_str(), FA_OPEN_EXISTING);
     if (result == FR_OK) {
       instance->setBackgroundImageFileName((char *)rootDir.c_str());
+      f_close(&file);
     } else {
       // TODO: This needs to be made user configurable, not
       // require the file be deleted to remove global background
@@ -315,6 +316,7 @@ void ThemeFile::applyBackground()
       result = f_open(&file, fileName, FA_OPEN_EXISTING);
       if (result == FR_OK) {
         instance->setBackgroundImageFileName(fileName);
+        f_close(&file);
       } else {
         instance->setBackgroundImageFileName("");
       }