Merge PR #385 (Fix stretched-grid regridding error)

This merge brings PR # (Fix the regridding error when
the target latitude or longitude is exactly 0.0, by @1Dandan)
into the GCPy 1.7.0 development stream.

PR #385 updates an if statement to use test for "None" instead
of "not", thus avoiding an error when the target latitude
or longitude is exactly zero.

Signed-off-by: Bob Yantosca <yantosca@seas.harvard.edu>

Author: yantosca

CHANGELOG.md

@@ -35,6 +35,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fixed grid area calculation scripts of `grid_area` in `gcpy/gcpy/cstools.py`
 - Fixed various security issues in GitHub Actions workflows
 - Fixed colorbar bounds for case of comparing cubed-sphere grids
+- Fixed the restart regridding for stretched GCHP when target lat/lon is exactly 0.0 in `gcpy/regrid_restart_file.py`
+
 
 ### Removed
 - Removed `PdfMerger()` from `compare_single_level` and `compare_zonal_mean`, it has been removed in pypdf >= 5.0.0

gcpy/regrid_restart_file.py

@@ -559,9 +559,9 @@ def regrid_restart_file(
         logging.info("Creating a stretched-grid restart file")
 
         if (
-            (not COMMAND_LINE.stretch_factor)
-            or (not COMMAND_LINE.target_latitude)
-            or (not COMMAND_LINE.target_longitude)
+            COMMAND_LINE.stretch_factor is None
+            or COMMAND_LINE.target_latitude is None
+            or COMMAND_LINE.target_longitude is None
         ):
             ERROR_MESSAGE = (
                 "--stretched-grid was set but not all stretched-"