Files: Fix windows compatibility

[jan-janssen]

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FAIL: test_load_guess_group (sphinx.test_base.TestSphinx.test_load_guess_group)
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Traceback (most recent call last):
  File "D:\a\pyiron_base\pyiron_atomistics\tests\sphinx\test_base.py", line 452, in test_load_guess_group
    self.assertEqual(guess.rho.file, '"' + rho_file + '"')
AssertionError: '"C:\\Users\\RUNNER~1\\AppData\\Local\\Temp\\tmp0wjq4yqz\\rho.sxb"' != '"C:\\Users\\RUNNER~1\\AppData\\Local\\Temp\\tmp0wjq4yqz/rho.sxb"'
- "C:\Users\RUNNER~1\AppData\Local\Temp\tmp0wjq4yqz\rho.sxb"
?                                                  ^
+ "C:\Users\RUNNER~1\AppData\Local\Temp\tmp0wjq4yqz/rho.sxb"
?                                                  ^


======================================================================
FAIL: test_run_complete (vasp.test_vasp.TestVasp.test_run_complete)
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Traceback (most recent call last):
  File "D:\a\pyiron_base\pyiron_atomistics\tests\vasp\test_vasp.py", line 423, in test_run_complete
    self.assertTrue(
AssertionError: False is not true

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[jan-janssen]

======================================================================
FAIL: test_run_complete (vasp.test_vasp.TestVasp.test_run_complete)
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Traceback (most recent call last):
  File "D:\a\pyiron_base\pyiron_atomistics\tests\vasp\test_vasp.py", line 423, in test_run_complete
    self.assertTrue(
AssertionError: False is not true
----------------------------------------------------------------------

[jan-janssen]

The issue was partially fixed by updating the tests in pyiron_atomistics in pyiron/pyiron_atomistics#1563 and pyiron/pyiron_atomistics#1564