upgrade the rtd config (#137)

* explicitly add the path to the sphinx config

* run on `python=3.12`

* require at least `sphinx>=6.0`

Author: keewis

.readthedocs.yaml

@@ -5,7 +5,7 @@ formats: []
 build:
   os: ubuntu-22.04
   tools:
-    python: "3.10"
+    python: "3.12"
   jobs:
     post_checkout:
       - (git --no-pager log --pretty="tformat:%s" -1 | grep -vqF "[skip-rtd]") || exit 183
@@ -18,3 +18,4 @@ python:
 
 sphinx:
   fail_on_warning: true
+  configuration: docs/conf.py

docs/requirements.txt

@@ -1,3 +1,3 @@
 packaging
-sphinx>=3.1
+sphinx>=6
 sphinx_rtd_theme