geotiff: importorskip tifffile in #1949 round-trip test

tifffile is not a runtime dep, so the unconditional module-level
import broke collection on CI where tifffile isn't installed.
Switch to ``pytest.importorskip`` to skip the file gracefully
instead, matching the pattern used by other geotiff tests
(``test_miniswhite_nodata_1809``, ``test_predictor3_big_endian``).
Also drop two unused stdlib imports.

Author: brendancol

xrspatial/geotiff/tests/test_no_georef_writer_round_trip_1949.py

@@ -20,15 +20,14 @@
 from __future__ import annotations
 
 import importlib.util
-import os
-import tempfile
 
 import numpy as np
 import pytest
-import tifffile
 import xarray as xr
 
-from xrspatial.geotiff import _coords_to_transform, open_geotiff, to_geotiff
+tifffile = pytest.importorskip("tifffile")
+
+from xrspatial.geotiff import _coords_to_transform, open_geotiff, to_geotiff  # noqa: E402
 
 
 def _gpu_available() -> bool: