[dvsim] Add python workaround for shutil
[dvsim] Add python workaround for shutil

Prior to Python 3.9, shutil may run into an error when passing in
Path objects (see https://bugs.python.org/issue32689). While this
has been fixed in Python 3.9, string casts are added so that this
also works with older versions.

Signed-off-by: Michael Schaffner <a005a2d3342a687ea2d05360c953107acbe83e08@google.com>

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