Pin the documentation dependencies' versions (#243)

This should make the documentation process more reliable and
reproducible across environments.

.readthedocs.yaml

@@ -17,6 +17,4 @@ python:
   install:
     - method: pip
       path: .
-# TODO: pin the development dependency versions
-# See https://docs.readthedocs.io/en/stable/guides/reproducible-builds.html
-#     - requirements: docs/requirements.txt
+    - requirements: requirements-docs.txt

MANIFEST.in

@@ -1,6 +1,6 @@
 include *.py
 include *.toml
-include requirements-dev.in
+include requirements-*.in
 include *.txt
 include CHANGES
 include COPYING

requirements-docs.in

@@ -0,0 +1,8 @@
+# The documentation-specific development dependencies.
+#
+# We generate requirements-dev.txt from this file by running
+#
+#     pip install -r requirements-docs.in && pip freeze > requirements-docs.txt
+#
+# and then modifying the file manually to restrict black and mypy to CPython
+sphinx

requirements-docs.txt

@@ -0,0 +1,24 @@
+alabaster==0.7.13
+Babel==2.14.0
+certifi==2023.11.17
+charset-normalizer==3.3.2
+docutils==0.20.1
+idna==3.6
+imagesize==1.4.1
+importlib-metadata==7.0.0
+Jinja2==3.1.2
+MarkupSafe==2.1.3
+packaging==23.2
+pygments==2.17.2
+pytz==2023.3.post1
+requests==2.31.0
+snowballstemmer==2.2.0
+sphinx==7.1.2
+sphinxcontrib-applehelp==1.0.4
+sphinxcontrib-devhelp==1.0.2
+sphinxcontrib-htmlhelp==2.0.1
+sphinxcontrib-jsmath==1.0.1
+sphinxcontrib-qthelp==1.0.3
+sphinxcontrib-serializinghtml==1.1.5
+urllib3==2.1.0
+zipp==3.17.0