nigthly CI: don't fail fast (#882)

Author: jstriebel

.github/workflows/nightly.yml

@@ -13,6 +13,7 @@ jobs:
       matrix:
         python-version: ["3.8", "3.9", "3.10"]
         group: [1, 2, 3]
+      fail-fast: false
     defaults:
       run:
         working-directory: webknossos