Add gitlab CI file

.gitlab-ci.yml

+stages:
+  - check
+  - build
+  - test
+  - deploy
+
+rust-lint:
+  image: rust
+  stage: check
+  script:
+  - rustup default nightly
+  - rustup component add rustfmt clippy
+  - rustup target install thumbv7m-none-eabi
+  - cargo fmt --all --check
+  - cargo clippy --all
+
+python-lint:
+  image: alpine
+  stage: check
+  script:
+  - apk add py3-flake8
+  - flake8
+
+build-rust:
+  image: rust
+  stage: build
+  script:
+  - rustup default nightly
+  - rustup target install thumbv7m-none-eabi
+  - cargo build --release
+  artifacts:
+    paths:
+      - target/thumbv7m-none-eabi/release/dc-motor-driver-hat
+
+test-rust:
+  image: rust
+  stage: test
+  script:
+  - rustup default nightly
+  - cd pid
+  - cargo test --target x86_64-unknown-linux-gnu
+
+deploy:
+  image: alpine
+  stage: deploy
+  script:
+  - mkdir firmware
+  - cp target/thumbv7m-none-eabi/release/dc-motor-driver-hat firmware/
+  - cp controller/python/controller.py firmware/
+  artifacts:
+    paths:
+      - firmware/