Add .gitlab-ci.yml

.gitlab-ci.yml

+before_script:
+  - curl https://sh.rustup.rs -sSf | sh -s -- -y --default-toolchain nightly
+
+build:
+  script:
+    - cargo build --release
+
+test:
+  script:
+  - cargo test --lib
+  - bash examples/run_examples.sh