Install version 1.0.0 of uMatrix:
https://addons.mozilla.org/de/firefox/addon/umatrix/versions/?page=1#version-1.0.0

Open the uMatrix Dashboard, all your settings and rules should be there. Now export these settings to a file, update to the latest Version of uMatrix and import the settings from the file you've just saved. Enjoy!

uMatrix is a great addon and I'm glad that the devs put in the effort to switch to web extensions. Your work is highly appreciated :)