1. Get DepotDownloader here https://github.com/SteamRE/DepotDownloader/releases
2. Unpack it somewhere and open cmd or powershell, navigate to the folder where you unpacked it (or shift right click in the folder and click open powershell window here)
3. type in "dotnet DepotDownloader.dll -app 788100 -depot 788101 -manifest <your wanted manifest version> -username <your steam username> -password <your steam password>" (WHY IT WANTS YOUR LOGIN: SteamDepotDownloader needs your identity so it can verify that you own the game.)

It will ask for your two-way authentication thingy if you have that enabled

You can find all the manifests here https://steamdb.info/depot/788101/manifests/

Below you'll find some of the versions I've tried, feel free to try them all out 7381836260294598856 = version 1.2.2.2 3671752282782031218 = 1.2.0.37 8317444412161278589 = 1.2.0.35 20364121041749679 = 1.2.0.34 3183472472810836949 = 1.1.13.19

After it's done downloading, you'll find it from depots > 788101 Delete your original game files and replace with these, and should be done if you did everything correctly

If you get an error saying "'dotnet' is not recognized as the name of a cmdlet", make sure you have .NET Core installed. You can get it here: https://dotnet.microsoft.com/download/dotnet/current