internal/vcs: use os.CopyFS from Go 1.23

We no longer need our simplified copy of CopyFS.

Signed-off-by: Daniel Martí <[email protected]>
Change-Id: I21c4b9b211129218c8a0bc2848652bd5bf256a73
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1209029
Unity-Result: CUE porcuepine <[email protected]>
Reviewed-by: Roger Peppe <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>

Author: mvdan

internal/vcs/copyfs_test.go

@@ -38,7 +38,7 @@ func TestGit(t *testing.T) {
 -- baz/something --
 `)))
 	qt.Assert(t, qt.IsNil(err))
-	err = copyFS(dir, testFS)
+	err = os.CopyFS(dir, testFS)
 	qt.Assert(t, qt.IsNil(err))
 
 	// In the tests that follow, we are testing the scenario where a module is