ci(actions-runner-images): update build context path for ubuntu image

- Changed the build context path from `./src/images/default` to `./src/images/ubuntu/default` in the actions-runner-images workflow.

Author: winromulus

.github/workflows/actions-runner-images.yaml

@@ -50,7 +50,7 @@ jobs:
       - name: build-and-push - ubuntu
         uses: docker/build-push-action@v3
         with:
-          context: ./src/images/default
+          context: ./src/images/ubuntu/default
           platforms: |
             linux/amd64
           tags: |