Update .gitlab-ci.yml file

.gitlab-ci.yml

+stages:
+  - lint
+  - build
+  - test
+
+variables:
+  CARGO_HOME: $CI_PROJECT_DIR/cargo
+  RUST_BACKTRACE: FULL
+  # Faster caching :)   
+  FF_USE_FASTZIP: "true"
+  CACHE_COMPRESSION_LEVEL: "fastest"
+
+# Linting
+cargo-fmt:
+  stage: lint
+  image: rust:latest
+  script:
+    - rustup component add rustfmt
+    - cargo fmt -- --check
+
+clippy:
+  stage: lint
+  image: rust:latest
+  script:
+    - rustup component add clippy
+    - cargo clippy -- -D warnings # Turn all warnings into errors
+
+# Building
+rust-stable:
+  stage: build
+  image: rust:stable
+  script:
+    - rustc --version && cargo --version
+    - cargo build --verbose
+
+# Testing
+test:
+  stage: test
+  image: rust:stable
+  script:
+    - rustc --version && cargo --version
+    - cargo test --verbose