Modernize RTD config

.readthedocs.yaml

@@ -1,11 +1,18 @@
+# Configuration on how ReadTheDocs (RTD) builds our documentation
+# ref: https://readthedocs.org/projects/2i2c-pilot-hubs/
+# ref: https://docs.readthedocs.io/en/stable/config-file/v2.html
+#
 version: 2
 
-conda:
-  environment: docs/environment.yml
-
 build:
-  image: latest
+  os: ubuntu-20.04
+  tools:
+    # NOTE: Update the python version hand in hand with the requirement
+    #       specification in docs/environment.yml
+    python: "3.8"
 
-python:
-  version: 3.8
-  install: []
+sphinx:
+  configuration: docs/source/conf.py
+
+conda:
+  environment: docs/environment.yml