chore(deps): upgrade dependency sphinx to v9

Author: renovate[bot]

pyproject.toml

@@ -57,7 +57,7 @@ docs = [
     "furo==2025.12.19",
     "levenshtein==0.27.3",
     "myst-parser[linkify]==4.0.1",
-    "sphinx==8.2.3",
+    "sphinx==9.1.0",
     "sphinx-autodoc-typehints==2.5.0",
     "sphinx-copybutton==0.5.2",
     "sphinx-intl==2.3.2",