docs: require newer Sphinx in RTD

bluetech · bluetech · commit 9abeeba57d1b · 2023-08-04T11:06:10.000+03:00
By default <2 is used, but we want to use new features. Refs #428
diff --git a/.readthedocs.yml b/.readthedocs.yml
@@ -5,6 +5,7 @@ python:
      # Without this, sphinx can't find pluggy's version.
      - method: pip
        path: .
+     - requirements: docs/requirements.txt
 
 build:
   os: ubuntu-22.04
diff --git a/docs/requirements.txt b/docs/requirements.txt
@@ -0,0 +1,4 @@
+# Higher bound for safety, can bump it if builds fine with new major versions.
+sphinx>=6,<8
+pygments
+towncrier
diff --git a/tox.ini b/tox.ini
@@ -22,9 +22,7 @@ deps=
 
 [testenv:docs]
 deps =
-  sphinx
-  pygments
-  towncrier
+    -r{toxinidir}/docs/requirements.txt
 commands =
   python scripts/towncrier-draft-to-file.py
   # the '-t changelog_towncrier_draft' tags makes sphinx include the draft
