Remove support for Python 3.8.

Python 3.8 has been deprecated upstream, and any tests depending on Homebrew already stopped working. Following our support policy, we are removing support for 3.8 from our packages, too.

PiperOrigin-RevId: 686012836
Change-Id: Ibd220eb9c10e9a74bbd4443c1d7286a1fde9e5e5

python/pyproject.toml

@@ -9,7 +9,7 @@ authors = [
     {name = "Google DeepMind", email = "mujoco@deepmind.com"},
 ]
 description = "MuJoCo Physics Simulator"
-requires-python = ">=3.8"
+requires-python = ">=3.9"
 license = {text = "Apache License 2.0"}
 classifiers = [
     "Development Status :: 5 - Production/Stable",
@@ -18,7 +18,6 @@ classifiers = [
     "License :: OSI Approved :: Apache Software License",
     "Natural Language :: English",
     "Programming Language :: Python :: 3",
-    "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",