docs(gp-sphinx) Bump gp-sphinx to v0.0.1a8 (#659)

Adopt gp-sphinx v0.0.1a8: ArgparseDomain, gp-sphinx-* CSS
namespace, sphinx>=8.1 floor, typed env.domains.* accessors, and
package renames (sphinx-autodoc-layout → sphinx-ux-autodoc-layout,
sphinx-autodoc-badges → sphinx-ux-badges).

See also: https://pypi.org/project/gp-sphinx/0.0.1a8/

Author: tony

CHANGES

@@ -43,6 +43,7 @@ _Notes on the upcoming release will go here._
 ### Documentation
 
 - Visual improvements to API docs from [gp-sphinx](https://gp-sphinx.git-pull.com)-based Sphinx packages (#658)
+- Bump gp-sphinx docs stack to v0.0.1a8 (#659)
 
 
 ### What's new

pyproject.toml

@@ -52,9 +52,9 @@ Changes = "https://github.com/tmux-python/libtmux/blob/master/CHANGES"
 [dependency-groups]
 dev = [
   # Docs (via gp-sphinx)
-  "gp-sphinx==0.0.1a7",
-  "sphinx-autodoc-api-style==0.0.1a7",
-  "sphinx-autodoc-pytest-fixtures==0.0.1a7",
+  "gp-sphinx==0.0.1a8",
+  "sphinx-autodoc-api-style==0.0.1a8",
+  "sphinx-autodoc-pytest-fixtures==0.0.1a8",
   "sphinx-autobuild",
   "types-docutils",
   # Testing
@@ -75,9 +75,9 @@ dev = [
 ]
 
 docs = [
-  "gp-sphinx==0.0.1a7",
-  "sphinx-autodoc-api-style==0.0.1a7",
-  "sphinx-autodoc-pytest-fixtures==0.0.1a7",
+  "gp-sphinx==0.0.1a8",
+  "sphinx-autodoc-api-style==0.0.1a8",
+  "sphinx-autodoc-pytest-fixtures==0.0.1a8",
   "sphinx-autobuild",
 ]
 testing = [