updated citation (#769)

Author: brendancol

README.md

@@ -283,4 +283,4 @@ With the introduction of projects like Numba, Python gained new ways to provide
 #### Citation
 Cite our code:
 
-`makepath/xarray-spatial, https://github.com/makepath/xarray-spatial, ©2020-2022.`
+`makepath/xarray-spatial, https://github.com/makepath/xarray-spatial, ©2020-2023.`