Update test_root_module Windows skip reason

The current cause of failure is different from what is documented
in the skip reason.

Author: EliahKagan

test/test_submodule.py

@@ -477,11 +477,11 @@ def test_base_bare(self, rwrepo):
     @skipIf(
         HIDE_WINDOWS_KNOWN_ERRORS,
         """
-        File "C:\\projects\\gitpython\\git\\cmd.py", line 559, in execute
-        raise GitCommandNotFound(command, err)
-        git.exc.GitCommandNotFound: Cmd('git') not found due to: OSError('[WinError 6] The handle is invalid')
-        cmdline: git clone -n --shared -v C:\\projects\\gitpython\\.git Users\\appveyor\\AppData\\Local\\Temp\\1\\tmplyp6kr_rnon_bare_test_root_module
-        """,  # noqa E501
+        E  PermissionError:
+        [WinError 32] The process cannot access the file because it is being used by another process:
+        'C:\\Users\\ek\\AppData\\Local\\Temp\\non_bare_test_root_modulep0eqt8_r\\git\\ext\\gitdb'
+        -> 'C:\\Users\\ek\\AppData\\Local\\Temp\\non_bare_test_root_modulep0eqt8_r\\path\\prefix\\git\\ext\\gitdb'
+        """,
     )
     @with_rw_repo(k_subm_current, bare=False)
     def test_root_module(self, rwrepo):