switch highest test version to 1.6

Author: j-fu

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
         version:
           - '1.3' # Replace this with the minimum Julia version that your package supports. E.g. if your package requires Julia 1.5 or higher, change this to '1.5'.
           - '1'   # Leave this line unchanged. '1' will automatically expand to the latest stable 1.x release of Julia.
-          - '1.7' # usually nigthly
+          - '1.6' # usually nigthly, but error-catching fails on windows
         os:
           - ubuntu-latest
           - macos-latest