Replace deprecated load_module in docs conf

SourceFileLoader.load_module is deprecated since 3.10 and gone in 3.15,
which the test matrix already covers. ty 0.0.75 started flagging it, and
the type environment runs with --error-on-warning, so main went red.

Author: gaborbernat

docs/conf.py

@@ -4,6 +4,7 @@
 import re
 from importlib.machinery import SourceFileLoader
 from pathlib import Path
+from types import ModuleType
 from typing import TYPE_CHECKING, Any
 
 from sphinx.domains.python import PythonDomain
@@ -173,7 +174,10 @@ def resolve_xref(  # ruff:ignore[too-many-arguments]
 
     app.connect("autodoc-process-signature", process_signature, priority=400)
     app.add_domain(PatchedPythonDomain, override=True)
-    tox_cfg = SourceFileLoader("tox_conf", str(here / "tox_conf.py")).load_module().ToxConfig
+    tox_conf_loader = SourceFileLoader("tox_conf", str(here / "tox_conf.py"))
+    tox_conf = ModuleType(tox_conf_loader.name)
+    tox_conf_loader.exec_module(tox_conf)
+    tox_cfg = tox_conf.ToxConfig
     app.add_directive(tox_cfg.name, tox_cfg)
 
     def check_uri(self: ExternalLinksChecker, refnode: reference) -> None: