diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7d85139..0b884db 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -28,6 +28,9 @@ jobs:
       posargs: --color=yes
       envs: |
         - linux: py312
+        - linux: py311
+        - linux: py310
+        - linux: py39
 
   test:
     needs: [core]
@@ -46,7 +49,7 @@ jobs:
   docs:
     uses: OpenAstronomy/github-actions-workflows/.github/workflows/tox.yml@main
     with:
-      default_python: '3.11'
+      default_python: '3.10'
       submodules: false
       pytest: false
       toxdeps: tox-pypi-filter
diff --git a/pyproject.toml b/pyproject.toml
index c337ce9..313fbc6 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -44,7 +44,6 @@ docs = [
   "sphinx-gallery>=0.13.0",
   "sphinxext-opengraph>=0.6.0",
   "sphinx-hoverxref>=1.3.0",
-  "sphinx-graphviz>=0.17.0",
 ]
 
 [tool.setuptools]