workflows: fail-fast false to let other builds run

Use fail-fast: false to let the non-failing matrix builds continue to
run.  Right now impish is timing out early in the process and we can't
see the results for the others.

Co-authored-by: Didier Roche <didrocks@ubuntu.com>

.github/workflows/build.yaml

@@ -6,6 +6,7 @@ jobs:
   test:
     runs-on: ubuntu-20.04
     strategy:
+      fail-fast: false
       matrix:
         image:
           - ubuntu-daily:bionic