add build.os for read the docs

Signed-off-by: Jeev B <jeevb@users.noreply.github.com>

.readthedocs.yml

@@ -5,12 +5,17 @@
 # Required
 version: 2
 
+# Build operating system
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.8"
+
 # Build documentation in the docs/ directory with Sphinx
 sphinx:
   configuration: conf.py
 
 # Optionally set the version of Python and requirements required to build your docs
 python:
-  version: 3.8
   install:
     - requirements: doc-requirements.txt