hot fix on read the docs

add build.os

.readthedocs.yml

@@ -1,5 +1,12 @@
 version: 2
 
+# Set the OS, Python version and other tools you might need
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.9"
+
+
 # Build documentation in the docs/ directory with Sphinx
 sphinx:
   configuration: docs/conf.py
@@ -9,7 +16,6 @@ formats: all
 
 # Optionally set the version of Python and requirements required to build your docs
 python:
-  version: 3.7
   install:
     - requirements: requirements.txt
     - requirements: docs/requirements-docs.txt