workflows: Add test to detect unused crates

The new workflow uses cargo-machete to detect unused crates.

Signed-off-by: Anderson Toshiyuki Sasaki <[email protected]>

Author: ansasaki

.github/workflows/cargo-machete.yml

@@ -0,0 +1,16 @@
+name: Check unused dependencies
+
+on:
+  pull_request:
+    paths:
+      - '**/Cargo.toml'
+      - '**/Cargo.lock'
+  workflow_dispatch:
+
+jobs:
+  check_unused_dependencies:
+    name: Check for unused dependencies
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: bnjbvr/cargo-machete@main