deps: Make Sphinx optional

Signed-off-by: Ryan Northey <[email protected]>

Author: phlax

.github/workflows/test.yml

@@ -45,6 +45,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           python -m pip install .[test]
+          python -m pip install .[standalone]
 
       - name: Test with pytest
         run: python -m pytest -vv --durations 25

pyproject.toml

@@ -39,9 +39,6 @@ classifiers = [
     "Topic :: Text Processing",
     "Topic :: Utilities",
 ]
-dependencies = [
-    "Sphinx>=5",
-]
 dynamic = ["version"]
 
 [project.optional-dependencies]
@@ -53,7 +50,9 @@ lint = [
     "mypy",
     "docutils-stubs",
 ]
-
+standalone = [
+  "sphinx > 5",
+]
 [[project.authors]]
 name = "Georg Brandl"
 email = "[email protected]"