build: add exceptiongroup dependency

Add the `exceptiongroup` dependency directly to Streamlink, so we
can write `ExceptionGroup` handling code on all supported versions
of Python without having to rely on `trio`'s conditional dependency.

docs/install.rst

@@ -442,6 +442,9 @@ Streamlink defines a `build system <pyproject.toml_>`__ according to `PEP-517`_
     * - runtime
       - `certifi`_
       - Used for loading the CA bundle extracted from the Mozilla Included CA Certificate List
+    * - runtime
+      - `exceptiongroup`_
+      - Used for ``ExceptionGroup`` handling, to allow writing async trio code on older Python versions.
     * - runtime
       - `isodate`_
       - Used for parsing ISO8601 strings
@@ -492,6 +495,7 @@ Streamlink defines a `build system <pyproject.toml_>`__ according to `PEP-517`_
 .. _versioningit: https://versioningit.readthedocs.io/en/stable/
 
 .. _certifi: https://certifiio.readthedocs.io/en/latest/
+.. _exceptiongroup: https://github.com/agronholm/exceptiongroup
 .. _isodate: https://pypi.org/project/isodate/
 .. _lxml: https://lxml.de/
 .. _pycountry: https://pypi.org/project/pycountry/

pyproject.toml

@@ -56,6 +56,7 @@ dynamic = [
 requires-python = ">=3.8"
 dependencies = [
   "certifi",
+  "exceptiongroup",
   "isodate",
   "lxml >=4.6.4,<6",
   "pycountry",

src/streamlink/compat.py

@@ -5,6 +5,9 @@ import sys
 import warnings
 from typing import Any, Callable, Dict, Optional, Tuple
 
+# import exceptiongroup, so it can monkeypatch ExceptionGroup logic on <=py311
+import exceptiongroup  # noqa: F401
+
 from streamlink.exceptions import StreamlinkDeprecationWarning
 
 

src/streamlink/session/session.py

@@ -3,6 +3,7 @@ import warnings
 from functools import lru_cache
 from typing import Any, Dict, Optional, Tuple, Type
 
+import streamlink.compat  # noqa: F401
 from streamlink import __version__
 from streamlink.exceptions import NoPluginError, PluginError, StreamlinkDeprecationWarning
 from streamlink.logger import StreamlinkLogger