Merge pull request #2019 from kivy/renovate/ubuntu-26.x

Update ubuntu Docker tag to v26

Author: AndreMiras

Dockerfile

@@ -28,7 +28,7 @@
 # Or simply recreate the directory from the host with:
 # rm -rf ~/.buildozer && mkdir ~/.buildozer
 
-FROM ubuntu:24.04
+FROM ubuntu:26.04
 
 ENV USER="user"
 ENV HOME_DIR="/home/${USER}"