Upgrade readthedocs image to the latest one

Armavica · twiecki · commit 223302882296 · 2024-09-17T12:23:17.000+08:00
diff --git a/.readthedocs.yaml b/.readthedocs.yaml
@@ -4,6 +4,6 @@ sphinx:
 conda:
   environment: doc/environment.yml
 build:
-  os: "ubuntu-20.04"
+  os: "ubuntu-lts-latest"
   tools:
-    python: "mambaforge-4.10"
+    python: "mambaforge-latest"
