[Dev] Unit test for `tempfile` alters test file in place

[DanielYang59]

Unit test for tempfile (test_tempfile.py) alters test file 3000_lines.txt.gz in place (because of re-gzip), could leadi to repeated commit of this file, for example in fd6b16ddde887573d1f8b986d00bdf5a2407f840.

Triggered by the following test: https://github.com/materialsvirtuallab/monty/blob/09d36926b6e613738adf19e61da61bc9f85f11e2/tests/test_tempfile.py#L47-L66