Skip dirs in copyArtifactSetRole and replace only basename

otherwise we get the error:

```
panic: open /efi/EFI/kairos/passive.efi.extra.d: is a directory
```

and we may replace parts of the path that we shouldn't.

Signed-off-by: Dimitris Karakasilis <dimitris@karakasilis.me>

pkg/uki/suite_test.go

@@ -0,0 +1,13 @@
+package uki_test
+
+import (
+	"testing"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+func TestActionSuite(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Uki test suite")
+}