[fix] Add quotes to the python version in readthedocs yaml file (#3121)

* [fix] Modify .yaml configuration to have build.os entry
* [fix] Add quotes to the python version in readthedocs yaml file

Author: alberttorosyan

.readthedocs.yaml

@@ -22,7 +22,6 @@ formats:
 
 # Optionally set the version of Python and requirements required to build your docs
 python:
-  version: 3.7
   install:
     - requirements: requirements.dev.txt
     - requirements: docs/requirements.txt