chore(deps): update dependency sphinx to v9

Author: renovate[bot]

setup.py

@@ -40,7 +40,7 @@
     ],
     extras_require={
         "docs": [
-            "sphinx>=8,<8.3",
+            "sphinx>=9,<9.1",
             "sphinx-rtd-theme>=3,<3.1",
             "myst-parser>=4,<4.1",
             "watchdog>=6,<6.1",