Change version to pre-release

Author: efaulhaber

Project.toml

@@ -1,7 +1,7 @@
 name = "PointNeighbors"
 uuid = "1c4d5385-0a27-49de-8e2c-43b175c8985c"
 authors = ["Erik Faulhaber <erik.faulhaber@uni-koeln.de>"]
-version = "0.2.1"
+version = "0.2.2-dev"
 
 [deps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"