Add .readthedocs.yaml file

Requesting to use the 'all' extra dependency to try to fix class references in the docs

Author: leszekhanusz

.readthedocs.yaml

@@ -0,0 +1,28 @@
+# .readthedocs.yaml
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+# Required
+version: 2
+
+# Set the version of Python and other tools you might need
+build:
+  os: ubuntu-20.04
+  tools:
+    python: "3.9"
+
+# Build documentation in the docs/ directory with Sphinx
+sphinx:
+   configuration: docs/conf.py
+
+# Optionally build your docs in additional formats such as PDF
+formats:
+  - pdf
+
+# Optionally declare the Python requirements required to build your docs
+python:
+  install:
+    - requirements: docs/requirements.txt
+
+  extra_requirements:
+    - all

MANIFEST.in

@@ -4,6 +4,7 @@ include CODEOWNERS
 include LICENSE
 include README.md
 include CONTRIBUTING.md
+include .readthedocs.yaml
 
 include dev_requirements.txt
 include Makefile