Removes broken gitlab CI script since it doesn't seem like anyone intends to fix the runner...

.gitlab-ci.yml

-image: "runner_grepit_lpc43xx:latest"
-
-stages:
-    - build
-
-debug:
-  stage: build
-  artifacts:
-    paths:
-      - target/thumbv7em-none-eabi/
-  tags: ["rust", "thumbv7em"]
-  before_script:
-    - tail memory.x -n 6 | head -n 5 > memory.x # dirty hack
-  script:
-    - cargo build --examples
-