bump(pre-release): version 0.5.1 > 0.5.2a1

Author: znicholls

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "pandas-openscm"
-version = "0.5.1"
+version = "0.5.2a1"
 description = "Pandas accessors for OpenSCM-related functionality."
 authors = [
     { name = "Zebedee Nicholls", email = "[email protected]" },