Downgrade docs build to Ubuntu 22

Ubuntu 24 no longer supports Python 3.7.
Its a lot of work to update the docs build to more modern python version

Author: AlexanderWells-diamond

.github/workflows/docs.yml

@@ -13,7 +13,7 @@ on:
 jobs:
   build:
     name: "Docs CI"
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
 
     steps:
       - name: Checkout Source