Add check for ma1sd repo changes on image self build

Adding when clause to ma1sd image build task to avoid image being built if not needed.

roles/matrix-ma1sd/tasks/setup_install.yml

@@ -87,6 +87,7 @@
       shell: "DOCKER_BUILDKIT=1 ./gradlew dockerBuild"
       args:
         chdir: "{{ matrix_ma1sd_docker_src_files_path }}"
+      when: matrix_ma1sd_git_pull_results.changed
 
     - name: Ensure ma1sd Docker image is tagged correctly
       docker_image: