Forager seem to be getting constant patches these days, and there is a period of time where users will be able to test the new patch before it is officially released. Right now the option is only available to Steam users, so console players and those who own the game on GOG are out of luck.
Anyway, to opt in for testing the beta version of the game, open Steam and locate the game in your game library. Right click on the game and select "Properties". Click on the tab that says "BETA" and select the "beta"-option from the drop down menu there.
Save the setting, and the newest beta version will automatically be installed / added to your game updates. Once this is downloaded and installed, you will automatically play the newest beta content the next time you open up the game.