How to replace the value of a string within two characters in php

Good morning everyone,
I need to figure out if there is a way to change the values inside the * *.

Example:

Hello everyone, this is my 1st post.
*photo1*
*photo2*
*photo3*
See you soon...

and replace the code with:

Hello everyone, this is my 1st post.
*photo*
*photo*
*photo*
See you soon...

without number after the word photo

How it works currently:

I have a txt file that contains the words photo1, photo2, photo3 between asterisks. This file is read via the file_get_contents command and I would need to remove the number at the end of the word photo.