Is Pluto still a dwarf planet? Recent news seem to suggest that astronomers are arguing about whether Pluto should become a planet again.

However, I cannot find an official source for this. Is this actually true?
Yes, Pluto is still a dwarf planet. According to the IAU website, it still fits the criteria for a dwarf planet, fails to meet the criteria for a planet, and still carries the "dwarf planet" label, whatever its future status may be. I'm sorry I can't provide a longer or more detailed answer, but this is really a yes-or-no question.