Upgrade colab base image to 20260226-060109 (#1542)

Users complaining about outdated CUDA
(https://admin.kaggle.com/competitions/nvidia-nemotron-model-reasoning-challenge/discussion/681820#3422400)

b/493600019

Author: tifftoff

Dockerfile.tmpl

@@ -1,7 +1,7 @@
 {{ if eq .Accelerator "gpu" }}
-FROM us-docker.pkg.dev/colab-images/public/runtime:release-colab-external_20260126-060048_RC00
+FROM us-docker.pkg.dev/colab-images/public/runtime:release-colab-external_20260226-060109_RC00
 {{ else }}
-FROM us-docker.pkg.dev/colab-images/public/cpu-runtime:release-colab-external_20260123-060023_RC00
+FROM us-docker.pkg.dev/colab-images/public/cpu-runtime:release-colab-external_20260226-060109_RC00
 {{ end}}
 
 ADD kaggle_requirements.txt /kaggle_requirements.txt