Bump version

Author: mfherbst

Project.toml

@@ -1,7 +1,7 @@
 name = "Libxc"
 uuid = "66e17ffc-8502-11e9-23b5-c9248d0eb96d"
 authors = ["Jason Eu <morty.yu@yahoo.com>", "Michael F. Herbst <info@michael-herbst.com>"]
-version = "0.3.20"
+version = "0.3.21"
 
 [deps]
 Libxc_GPU_jll = "25af9330-9b41-55d4-a324-1a83c0a0a1ac"