[synpy-1542] Upgrade readthedocs os, python version, and search ranking (#1184)

Author: BryanFauble

.readthedocs.yaml

@@ -6,9 +6,10 @@ version: 2
 
 # Set the version of Python and other tools you might need
 build:
-  os: ubuntu-20.04
+  os: ubuntu-22.04
   tools:
-    python: "3.9"
+    # alias for the latest 3.x version available on Read the Docs
+    python: "3"
 
 mkdocs:
   configuration: mkdocs.yml
@@ -17,3 +18,8 @@ mkdocs:
 python:
   install:
   - requirements: docs/requirements.txt
+
+# See https://docs.readthedocs.com/platform/stable/config-file/v2.html#search for more options
+search:
+  ranking:
+    reference/*: -1