Set version number to 0.0.1 (#84)

To avoid committing to semantic versioning at this point, we will
start making releases with major number 0. The 0.0.x releases will
be used to test our release process and CI infrastructure.

Until major version 1 is released, pytopotoolbox should be considered
unstable and subject to change.

pyproject.toml

@@ -9,7 +9,7 @@ requires = [
 
 [project]
 name = "topotoolbox"
-version = "3.0.1"
+version = "0.0.1"
 authors = [
     {name="Wolfgang Schwanghart", email="[email protected]"},
     {name="Dirk Scherler", email="[email protected]"},