[Quality] Automatically get version

pyproject.toml

@@ -0,0 +1,4 @@
+
+[build-system]
+requires = ["setuptools"]
+build-backend = "setuptools.build_meta"

setup.py

@@ -4,6 +4,7 @@
 #  LICENSE file in the root directory of this source tree.
 #
 import os
+import pathlib
 from pathlib import Path
 
 from setuptools import find_packages, setup
@@ -17,6 +18,19 @@ def package_files(directory):
     return paths
 
 
+def get_version():
+    """Gets the benchmarl version."""
+    path = CWD / "benchmarl" / "__init__.py"
+    content = path.read_text()
+
+    for line in content.splitlines():
+        if line.startswith("__version__"):
+            return line.strip().split()[-1].strip().strip('"')
+    raise RuntimeError("bad version data in __init__.py")
+
+
+CWD = pathlib.Path(__file__).absolute().parent
+
 extra_files = package_files(
     str(
         Path(os.path.dirname(os.path.realpath(__file__)))
@@ -27,7 +41,7 @@ def package_files(directory):
 
 setup(
     name="benchmarl",
-    version="1.1.1",
+    version=get_version(),
     description="BenchMARL",
     url="https://github.com/facebookresearch/BenchMARL",
     author="Matteo Bettini",