I’ve never actually done it, because the only extension I use is Blur My Shell, and the dev is so quick at updating that extension that even when I immediately update to a beta release it’s already marked as compatible, but here it is:

gsettings set org.gnome.shell disable-extension-version-validation true

And if you want to revert back to normal and have extensions be validated again:

gsettings reset org.gnome.shell disable-extension-version-validation

I don’t know if there’s a GUI way to do it in one of the extension management platforms, I’ve never really looked