chore(deps): update dependency readthedocs/ubuntu to v26 (#475)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.readthedocs.yaml

@@ -5,7 +5,7 @@
 version: 2
 
 build:
-  os: ubuntu-24.04
+  os: ubuntu-26.04
   tools:
     ruby: "3.3"
   jobs: