Fix doc issue

Issue-ID: SO-4084
Signed-off-by: Lukasz Rajewski <lukasz.rajewski@t-mobile.pl>
Change-Id: Id1e1b8e8be474eef7bf43b9f3a89d7ed2a316552
(cherry picked from commit 7872038bd9a678546a596c570ae8c179ab056216)
diff --git a/.readthedocs.yaml b/.readthedocs.yaml
index 9c22c0b..6b02eb3 100644
--- a/.readthedocs.yaml
+++ b/.readthedocs.yaml
@@ -27,10 +27,11 @@
   - htmlzip
 
 build:
-  image: latest
+  os: ubuntu-20.04
+  tools:
+    python: "3.8"
 
 python:
-  version: 3.7
   install:
     - requirements: docs/requirements-docs.txt