feat(py-exceptiongroup): copy package from upstream

packages/py-exceptiongroup/package.py

+# Copyright 2013-2024 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+
+from spack.package import *
+
+
+class PyExceptiongroup(PythonPackage):
+    """A backport of the BaseExceptionGroup and ExceptionGroup classes from Python 3.11."""
+
+    homepage = "https://github.com/agronholm/exceptiongroup"
+    pypi = "exceptiongroup/exceptiongroup-1.0.4.tar.gz"
+
+    version("1.1.1", sha256="d484c3090ba2889ae2928419117447a14daf3c1231d5e30d0aae34f354f01785")
+    version("1.0.4", sha256="bd14967b79cd9bdb54d97323216f8fdf533e278df937aa2a90089e7d6e06e5ec")
+
+    depends_on("py-flit-scm", type="build")