move build specification higher

.readthedocs.yml

@@ -9,19 +9,21 @@ version: 2
 sphinx:
   configuration: docs/conf.py
 
+# Specify the build os and python version
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.9"
+
 # Build documentation with MkDocs
 #mkdocs:
 #  configuration: mkdocs.yml
 
 # Optionally build your docs in additional formats such as PDF
 formats: []
 
-# Optionally set the version of Python and requirements required to build your docs
-build:
-  os: ubuntu-22.04
-  tools:
-    python: "3.9"
 
+# Optionally set the Python requirements required to build your docs
 python:
   install:
   - requirements: docs/requirements.txt