updated readthedocs.yml file

Signed-off-by: Dinesh Dutt <[email protected]>

Author: ddutt

.readthedocs.yml

@@ -3,6 +3,11 @@ mkdocs:
   configuration: mkdocs.yml
 
 python:
-  version: 3.7
+  version: 3.9
   install:
     - requirements: docs/requirements.txt
+
+build:
+    os: ubuntu-20.04
+    tools:
+      python: 3.9