bump docs dependencies

.readthedocs.yml

@@ -0,0 +1,5 @@
+version: 2
+
+python:
+  install:
+  - requirements: requirements-docs.txt

docs/conf.py

@@ -38,6 +38,7 @@ extensions = [
     "sphinx.ext.autodoc",
     "sphinx.ext.doctest",
     "sphinx.ext.intersphinx",
+    "sphinx_rtd_theme",
 ]
 
 # Add any paths that contain templates here, relative to this directory.

newsfragments/70.internal.rst

@@ -1 +0,0 @@
-Do not invoke ``setup.py`` directly. Minor cleanup and refactors in newsfragment ``README.md`` and newsfragment validation. Minot cleanup in ``Makefile``.

setup.py

@@ -19,9 +19,9 @@ extras_require = {
         "black>=22",
     ],
     "doc": [
-        "Sphinx>=1.6.5",
-        "sphinx_rtd_theme>=0.1.9",
-        "towncrier>=21",
+        "sphinx>=5.0.0",
+        "sphinx_rtd_theme>=1.0.0",
+        "towncrier>=21,<22",
     ],
     "dev": [
         "bumpversion>=0.5.3",