welcome to doc dependency hell

sphinx-rtd-theme 2.0.0 declares that it is incompatible with sphinx 8.
As a result, with the old requirements-dev.txt, sphinx 8 and
sphinx-rtd-theme 0.mumble are installed, as sphinx-rtd-theme 0.mumble did
NOT declare an explicit incompatibility with sphinx 8.

This pairing emphatically does NOT work, giving the error
`UndefinedError("'style' is undefined")` during doc building.

For all these AWESOME packages, specify a dependency range.
This is sure to prevent future breakage 😉

doc/conf.py

@@ -16,8 +16,10 @@ import os
 import re
 import subprocess
 import sys
+import pathlib
 
-sys.path.insert(0, os.path.abspath("."))
+ROOT = pathlib.Path(__file__).absolute().parent.parent
+sys.path.insert(0, str(ROOT / "src"))
 
 
 # -- Project information -----------------------------------------------------

requirements-dev.txt

@@ -14,9 +14,9 @@ pre-commit
 python-dateutil
 requests; implementation_name=="cpython"
 setuptools>=68; implementation_name=="cpython"
-sphinx
-sphinx-autodoc-typehints
-sphinx-rtd-theme
+sphinx>=8.0.2,<9
+sphinx-autodoc-typehints>=2.4.1,<3
+sphinx-rtd-theme>=3.0.0rc1,<4
 twine; implementation_name=="cpython"
 types-beautifulsoup4; implementation_name=="cpython"
 types-python-dateutil; implementation_name=="cpython"