grdsample (pixel to gridline) returns nans

### Description of the problem

When using the grdsample routine to translate from pixel registration to gridline registration, the output contains nans at the poles. This does not occur when using the GMT command line utilities.

### Minimal Complete Verifiable Example

```python
import numpy as np
import pygmt

ppd = 1 # pixels per degree
nlat = 180 * ppd + 1
nlon = 360 * ppd + 1
array = np.ones((nlat, nlon))
spacing = 1 / ppd

x = np.arange(0, 360 + spacing, spacing)
y = np.arange(-90, 90 + spacing, spacing)
xx, yy = np.meshgrid(x, y)

# create gridline registered dataset
gridline = pygmt.xyz2grd(x=xx.flatten(), y=yy.flatten(), z=array.flatten(), spacing=spacing, region=[0, 360, -90, 90], registration='g', coltypes="g")

# convert to pixel registered
pixel = pygmt.grdsample(grid=gridline, translate=True)

# convert back to gridline registered
gridline2 = pygmt.grdsample(grid=pixel, translate=True)

print(gridline)
print(pixel)
print(gridline2)
```

### Full error message

```python-traceback

array([[1., 1., 1., ..., 1., 1., 1.],
[1., 1., 1., ..., 1., 1., 1.],
[1., 1., 1., ..., 1., 1., 1.],
...,
[1., 1., 1., ..., 1., 1., 1.],
[1., 1., 1., ..., 1., 1., 1.],
[1., 1., 1., ..., 1., 1., 1.]], dtype=float32)
Coordinates:
* lon (lon) float64 0.0 1.0 2.0 3.0 4.0 ... 356.0 357.0 358.0 359.0 360.0
* lat (lat) float64 -90.0 -89.0 -88.0 -87.0 -86.0 ... 87.0 88.0 89.0 90.0
Attributes:
long_name: z
actual_range: [1. 1.]

array([[1.008623 , 0.99907345, 1. , ..., 1. , 1. ,
1.0083693 ],
[1. , 1. , 1. , ..., 1. , 1. ,
0.99901193],
[1. , 1. , 1. , ..., 1. , 1. ,
1. ],
...,
[1. , 1. , 1. , ..., 1. , 1. ,
1. ],
[1. , 1. , 1. , ..., 1. , 1. ,
1. ],
[1. , 1. , 1. , ..., 1. , 1. ,
1. ]], dtype=float32)
Coordinates:
* lon (lon) float64 0.5 1.5 2.5 3.5 4.5 ... 355.5 356.5 357.5 358.5 359.5
* lat (lat) float64 -89.5 -88.5 -87.5 -86.5 -85.5 ... 86.5 87.5 88.5 89.5
Attributes:
long_name: z
actual_range: [0.99901193 1.008623 ]

array([[ nan, nan, nan, ..., nan, nan,
nan],
[1.0020888 , 1.0023468 , 0.99943876, ..., 0.99975574, 1.0018516 ,
1.0020888 ],
[0.99972796, 0.9997256 , 1.0000663 , ..., 1.0000675 , 0.99908644,
0.99972796],
...,
[1. , 1. , 1. , ..., 1. , 1. ,
1. ],
[1. , 1. , 1. , ..., 1. , 1. ,
1. ],
[ nan, nan, nan, ..., nan, nan,
nan]], dtype=float32)
Coordinates:
* lon (lon) float64 0.0 1.0 2.0 3.0 4.0 ... 356.0 357.0 358.0 359.0 360.0
* lat (lat) float64 -90.0 -89.0 -88.0 -87.0 -86.0 ... 87.0 88.0 89.0 90.0
Attributes:
long_name: z
actual_range: [0.99908644 1.00234675]
```

### System information

```bash
PyGMT information:
version: v0.11.0
System information:
python: 3.12.1 | packaged by conda-forge | (main, Dec 23 2023, 08:01:35) [Clang 16.0.6 ]
executable: /Users/lunokhod/miniconda3/envs/py312/bin/python
machine: macOS-14.3-arm64-arm-64bit
Dependency information:
numpy: 1.26.3
pandas: 2.1.4
xarray: 2023.12.0
netCDF4: 1.6.5
packaging: 23.2
contextily: None
geopandas: None
ipython: None
rioxarray: None
ghostscript: 10.02.1
GMT library information:
binary version: 6.5.0
cores: 10
grid layout: rows
image layout:
library path: /Users/lunokhod/miniconda3/envs/py312/lib/libgmt.dylib
padding: 2
plugin dir: /Users/lunokhod/miniconda3/envs/py312/lib/gmt/plugins
share dir: /Users/lunokhod/miniconda3/envs/py312/share/gmt
version: 6.5.0
```