py(deps[docs]): Pin sphinx<9 to avoid breaking changes

why: Sphinx 9.x introduced breaking changes that affect sphinxarg/ext.py
(mock() function moved to internal _dynamic package) and mypy fails on
PEP 695 type statement syntax.
what:
- Add sphinx<9 constraint to dev and docs dependency groups
- Update uv.lock to use sphinx 8.x

Author: tony

pyproject.toml

@@ -66,7 +66,7 @@ Repository = "https://github.com/cihai/cihai-cli"
 [dependency-groups]
 dev = [
   # Docs
-  "sphinx",
+  "sphinx<9",
   "furo",
   "gp-libs",
   "sphinx-autobuild",
@@ -98,7 +98,7 @@ dev = [
 ]
 
 docs = [
-  "sphinx",
+  "sphinx<9",
   "furo",
   "gp-libs",
   "sphinx-autobuild",