ci: make sure to always run tests against full matrix

Otherwise a failing test will cancel the other test runs, making
it more difficult to figure out if a failure is platform specific.

Author: foosel

.github/workflows/main.yml

@@ -19,6 +19,7 @@ jobs:
     runs-on: ${{ matrix.platform }}
 
     strategy:
+      fail-fast: false
       matrix:
         platform: [ubuntu-latest, macos-latest, windows-latest]