Revert "bump version for release 0.9.0"

This reverts commit 0b767d4.

Author: ElliottKasoar

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "janus-core"
-version = "0.9.0"
+version = "0.8.7"
 description = "Tools for machine learnt interatomic potentials"
 authors = [
     { name = "Elliott Kasoar" },