Only test on Linux

The package doesn't have any binary dependendencies so there is
not much value in testing on all platforms except sometimes
detecting issues in test dependencies.

Author: andreasnoack

.github/workflows/ci.yml

@@ -18,8 +18,6 @@ jobs:
           - 'pre'
         os:
           - ubuntu-latest
-          - macOS-latest
-          - windows-latest
         arch:
           - x64
           - x86