CI: Check format before running test

Testing needs compilation and is slow. Format checking is quick.
As format checking fails more often than tests,
switching them should result in faster failure and feedback

.gitlab-ci.yml

@@ -30,8 +30,8 @@ test:cargo:
     - rustup component add clippy rustfmt
   script:
     - rustc --version && cargo --version  # Print version info for debugging
-    - cargo test --workspace --verbose --locked
     - cargo fmt --all -- --check
+    - cargo test --workspace --verbose --locked
     - cargo clippy
 
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