Run the TestInit.test_nofilematch test in a tempdir

[xiki-tempula]

The current test is

    def test_nofilematch(self):
        with pytest.raises(ValueError, match="No file has been matched to"):
>           ABFE(
                dir="./",
                prefix="dhdl",
                suffix="xvg",
                T=310,
            )

Which is fine it's own sense but will try to search through all the subfolders in dir="./". So if you run it in your root path '~', it will try to access all the files which might annoy some security people. Once I had time should make a temp dir for this test.