Add __version__ variable for python library (#308)

[PEP 396](https://peps.python.org/pep-0396/)

---------

Co-authored-by: AliceMazzoleni99 <alice.mazzoleni@psi.ch>

python/aare/__init__.py

@@ -13,6 +13,7 @@ from ._aare import corner
 
 # from ._aare import ClusterFinderMT, ClusterCollector, ClusterFileSink, ClusterVector_i
 
+from ._version import __version__
 from .ClusterFinder import ClusterFinder, ClusterCollector, ClusterFinderMT, ClusterFileSink, ClusterFile
 from .ClusterVector import ClusterVector
 from .Cluster import Cluster

python/aare/_version.py

@@ -0,0 +1,8 @@
+# This file is used to get the version of the package from the VERSION file
+from importlib.metadata import PackageNotFoundError, version
+from pathlib import Path
+
+try:
+    __version__ = version('aare')
+except PackageNotFoundError:
+    __version__ = Path(__file__).parents[2].joinpath('VERSION').read_text().strip()