TST: replace ensure_clean with temp_file in pandas/tests/io/formats/t…

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TST: replace ensure_clean with temp_file in pandas/tests/io/formats/test_to_csv.py (xref pandas-dev#62435)

What:
Replace tm.ensure_clean usage with the pytest temp_file fixture (and tmp_path where a specific extension was required) in
pandas/tests/io/formats/test_to_csv.py.

Why:
The project standard is to use the temp_file pytest fixture instead of the legacy ensure_clean helper. This PR is a small, focused change toward the larger effort tracked in issue pandas-dev#62435.

Changes:

• Replaced usages of ensure_clean / tm.ensure_clean with the pytest temp_file fixture.
• Where tests required a specific file extension (e.g. .zip, .gz, etc.), used temp_file.with_suffix(...).
• Where downstream APIs required a string path, used str(path) explicitly to preserve compatibility.
• No functional test logic changes; only temporary-file helper replacement.

Files changed:

• pandas/tests/io/formats/test_to_csv.py

Examples of edits:

• test_to_csv_with_single_column: now accepts temp_file fixture and writes/reads from it directly.
• compression tests: use temp_file.with_suffix("." + extension) for extension-specific files.
• binary-handle tests: continue to open the temp_file as before but using the fixture-provided Path.

Local verification:
I ran the modified tests locally and verified the file and individual tests pass:

• Run the whole file:
  pytest -q pandas/tests/io/formats/test_to_csv.py
  (All tests in the file passed locally.)

• Run an individual test:
  pytest -q pandas/tests/io/formats/test_to_csv.py::TestToCSV::test_to_csv_with_single_column
  (This test passed locally.)

Pre-commit hooks:

• Ran pre-commit locally:
  pre-commit run --all-files
  (All configured checks passed.)

Notes:

• This PR only updates test code and preserves test semantics.
• The change is intended to be a small, direct replacement and does not close the overall issue; it is part of the multi-PR effort to address:
  TST: Replace ensure_clean utility function with the temp_file pytest fixture TST: Replace ensure_clean utility function with the temp_file pytest fixture pandas-dev/pandas#62435 (xref TST: Replace ensure_clean utility function with the temp_file pytest fixture pandas-dev/pandas#62435).

Related:

• xref: TST: Replace ensure_clean utility function with the temp_file pytest fixture TST: Replace ensure_clean utility function with the temp_file pytest fixture pandas-dev/pandas#62435

• Related assist PR: TST: Assist Replace ensure_clean utility function with the temp_file pytest fixture #62435 pandas-dev/pandas#62461

• closes TST: Replace ensure_clean utility function with the temp_file pytest fixture pandas-dev/pandas#62435

• Tests added and passed if fixing a bug or adding a new feature

• [√] All code checks passed.

• Added type annotations to new arguments/methods/functions.

• Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.