update rtd config

.readthedocs.yml

@@ -5,15 +5,20 @@
 # Required
 version: 2
 
-# Build documentation in the docs/ directory with Sphinx
+build:
+    os: "ubuntu-22.04"
+    tools:
+        python: "3.10"
+
+# Build documentation in the doc/ directory with Sphinx
 sphinx:
     configuration: doc/conf.py
 
-# Optionally build your docs in additional formats such as PDF
-formats: all
+# Optionally build your docs in additional formats such as PDF and ePub
+# formats: all
 
 # Optionally set the version of Python and requirements required to build your docs
 python:
-    version: 3
     install:
         - requirements: doc/rtd-requirements.txt
+