.readthedocs.yml: Upgrade python & pip (#2653)

Author: adriendupuis

.readthedocs.yml

@@ -7,9 +7,8 @@ mkdocs:
 build:
   os: ubuntu-20.04
   tools:
-    python: "3.11"
+    python: "3.13"
 
 python:
   install:
-    - requirements: pip_require.txt
     - requirements: requirements.txt