Remove Basemap dependency

[Ghazal-Mohammadpour]

Description

This PR removes the Basemap dependency from the code. Basemap is being deprecated because Cartopy provides similar functionality for plotting geographic data.

Changes:

• Removed Basemap import statement and associated code.

Explanation

• Basemap functionality has been replaced with equivalent functionality from Cartopy.
• The code remains fully functional and produces the same visual output without relying on Basemap.

[JessicaMeixner-NOAA]

@ricampos please let us know if this will cause any issues or if something needs to be added in its place. Based on this PR it looks like these functions aren't really used, but I could definitely be reading the code incorrectly. We do not want to break anything, but would like to remove basemap.

[ricampos]

Hi. It is ok, it is a good udpate. The pvalstats.py will take the pallete from matplotlib.pyplot.
I see only pvalstats.py was modified. The same can be done with ww3tools/organizeDistanceToCoast.py (it is not an important code, but since we are doing this ...)
And ww3tools/gridSatGlobal_Altimeter.py and ww3tools/prepGridMask.py are using the shiftgrid from basemap
from mpl_toolkits.basemap import shiftgrid
which can be replaced with another shiftgrid function somehow (I haven't tried yet)

[JessicaMeixner-NOAA]

It looks like the update to ww3tools/organizeDistanceToCoast.py is equally as simple, so updating that in this PR is a great idea. The shiftgrid function is a more complicated update, so I recommend us creating an issue so that we can track the need to do this, but holding off on that for another PR. Does that sound okay @ricampos ?

[ricampos]

Yes. I agree. Thank you

[JessicaMeixner-NOAA]

Issue #64 has been created to track the shiftgrid.

@Ghazal-Mohammadpour let me know if you have any questions about also removing basemap from ww3tools/organizeDistanceToCoast.py in this PR.

[JessicaMeixner-NOAA]

@ricampos - @Ghazal-Mohammadpour has made the changes and we made the new issue for shiftgrid.

[ricampos]

Perfect. I can see the modifications. Thank you