Add packages to setup.py (#250)

setup.py

@@ -1,4 +1,4 @@
-from setuptools import setup
+from setuptools import find_packages, setup
 
 with open("README.md") as fh:
     long_description = ""
@@ -31,7 +31,7 @@ setup(
     url="https://github.com/Farama-Foundation/MiniGrid",
     description="Minimalistic gridworld reinforcement learning environments",
     extras_require=extras,
-    packages=["minigrid", "minigrid.envs"],
+    packages=[package for package in find_packages() if package.startswith("minigrid")],
     entry_points={
         "gymnasium.envs": ["__root__ = minigrid.__init__:register_minigrid_envs"]
     },