test: run `entrypoint` test on Linux
This forces the `@which-echo` repository to run which will fail when there is no `echo` on `PATH`. That is the case on Windows. It is not guaranteed that `echo` is on `PATH` on Linux but highly likely.
This forces the `@which-echo` repository to run which will fail when there is no `echo` on `PATH`. That is the case on Windows. It is not guaranteed that `echo` is on `PATH` on Linux but highly likely.