Merge remote-tracking branch 'origin/v0.3.1-release' into v0.3.1-release

Author: willschlitzer

doc/changes.md

@@ -2,7 +2,7 @@
 
 ## Release v0.3.1 (2021/03/14)
 
-[![Digital Object Identifier for PyGMT v0.3.1](https://zenodo.org/badge/DOI/10.5281/zenodo.3781524.svg)](https://doi.org/10.5281/zenodo.3781524)
+[![Digital Object Identifier for PyGMT v0.3.1](https://zenodo.org/badge/DOI/10.5281/zenodo.4592991.svg)](https://doi.org/10.5281/zenodo.4592991)
 
 ### Highlights