Update .readthedocs.yml

.readthedocs.yml

@@ -1,26 +1 @@
-version: 2
 
-python:
-   install:
-     # Install pytest first, then doc/en/requirements.txt.
-     # This order is important to honor any pins in doc/en/requirements.txt
-     # when the pinned library is also a dependency of pytest.
-     - method: pip
-       path: .
-     - requirements: doc/en/requirements.txt
-
-sphinx:
-  configuration: doc/en/conf.py
-  fail_on_warning: true
-
-build:
-  os: ubuntu-20.04
-  tools:
-    python: "3.9"
-  apt_packages:
-    - inkscape
-
-formats:
-  - epub
-  - pdf
-  - htmlzip