Update Read The Docs configuration to support Python 3.8 (#439)

* Use the latest build image for readthedocs

Signed-off-by: Gigon Bae <gbae@nvidia.com>

* Use the latest configuration for readthedocs

Signed-off-by: Gigon Bae <gbae@nvidia.com>

---------

Signed-off-by: Gigon Bae <gbae@nvidia.com>

Author: gigony

.readthedocs.yml

@@ -1,28 +1,35 @@
-# .readthedocs.yml
-# Read the Docs configuration file
+# Read the Docs configuration file for Sphinx projects
 # See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
 
 # Required
 version: 2
 
-# Build documentation in the docs/ directory with Sphinx
+# Set the OS, Python version and other tools you might need
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.8"
+    # You can also specify other tool versions:
+    # nodejs: "20"
+    # rust: "1.70"
+    # golang: "1.20"
+
+# Build documentation in the "docs/" directory with Sphinx
 sphinx:
   configuration: docs/source/conf.py
-
-# Build documentation with MkDocs
-#mkdocs:
-#  configuration: mkdocs.yml
+  # You can configure Sphinx to use a different builder, for instance use the dirhtml builder for simpler URLs
+  # builder: "dirhtml"
+  # Fail on all warnings to avoid broken references
+  # fail_on_warning: true
 
 # Optionally build your docs in additional formats such as PDF and ePub
-# formats: all
+# formats:
+#    - pdf
+#    - epub
 
-# Optionally set the version of Python and requirements required to build your docs
+# Optional but recommended, declare the Python requirements required
+# to build your documentation
+# See https://docs.readthedocs.io/en/stable/guides/reproducible-builds.html
 python:
-  version: "3.8"
-  install:
-    - requirements: docs/requirements.txt
-#  system_packages: true
-
-
-build:
-  image: stable
+   install:
+   - requirements: docs/requirements.txt