change xarray version for travis

Author: Japhiolite

setup.py

@@ -22,7 +22,8 @@
         'pyvistaqt',
         'pyqt5',
         'iPython',
-        'pandas==1.3.4'
+        'pandas==1.3.4',
+        'xarray==2022.3.0'
     ],
     url='https://github.com/cgre-aachen/gempy',
     license='LGPL v3',