Solution for strange error after new gmod update

If you get an error when trying to start your server that says "No entry point found" / SteamInternal_FindOrCreateUserInterface or some other startup-related strange error after you tried to install the new update then I've found a possible fix.

Copy the steam_api.dll (which is in the /bin/ folder) to the Garry's Mod main directory (where the srcds.exe is). I wasted an entire day to find that fix.

I hope I was able to help someone.