Add cargo fmt to the pipeline

Signed-off-by: Nikolai Rodionov <allanger@badhouseplants.net>

.woodpecker/code_tests.yaml

@@ -7,6 +7,11 @@ steps:
     commands:
       - rustup component add clippy
       - cargo clippy
+  - name: Rust fmt
+    image: rust:1.91.1-bullseye
+    commands:
+      - rustup component add rustfmt
+      - cargo fmt --check
   - name: Unit tests
     image: rust:1.91.1-bullseye
     commands: